stmmac: platform: fix sparse warnings

This patch fixes the following sparse warnings. One is fixed by casting return
value to a return type of the function. The others by creating a specific
stmmac_platform.h which provides the bits related to the platform driver.

drivers/net/ethernet/stmicro/stmmac/dwmac-meson.c:59:29: warning: incorrect type in return expression (different address spaces)
drivers/net/ethernet/stmicro/stmmac/dwmac-meson.c:59:29: expected void *
drivers/net/ethernet/stmicro/stmmac/dwmac-meson.c:59:29: got void [noderef] <asn:2>*reg

drivers/net/ethernet/stmicro/stmmac/dwmac-meson.c:64:29: warning: symbol 'meson6_dwmac_data' was not declared. Should it be static?
drivers/net/ethernet/stmicro/stmmac/dwmac-sti.c:354:29: warning: symbol 'stih4xx_dwmac_data' was not declared. Should it be static?
drivers/net/ethernet/stmicro/stmmac/dwmac-sti.c:361:29: warning: symbol 'stid127_dwmac_data' was not declared. Should it be static?
drivers/net/ethernet/stmicro/stmmac/dwmac-sunxi.c:133:29: warning: symbol 'sun7i_gmac_data' was not declared. Should it be static?

Signed-off-by: Andy Shevchenko <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/stmicro/stmmac/dwmac-meson.c

···
 #include <linux/platform_device.h>
 #include <linux/stmmac.h>
 
+#include "stmmac_platform.h"
+
 #define ETHMAC_SPEED_100	BIT(1)
 
 struct meson_dwmac {
···
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 	dwmac->reg = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(dwmac->reg))
-		return dwmac->reg;
+		return ERR_CAST(dwmac->reg);
 
 	return dwmac;
 }

drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c

···
 #include <linux/regmap.h>
 #include <linux/reset.h>
 #include <linux/stmmac.h>
+
 #include "stmmac.h"
+#include "stmmac_platform.h"
 
 #define SYSMGR_EMACGRP_CTRL_PHYSEL_ENUM_GMII_MII 0x0
 #define SYSMGR_EMACGRP_CTRL_PHYSEL_ENUM_RGMII 0x1

drivers/net/ethernet/stmicro/stmmac/dwmac-sti.c

···
 #include <linux/of.h>
 #include <linux/of_net.h>
 
+#include "stmmac_platform.h"
+
 #define DWMAC_125MHZ	125000000
 #define DWMAC_50MHZ	50000000
 #define DWMAC_25MHZ	25000000

drivers/net/ethernet/stmicro/stmmac/dwmac-sunxi.c

···
 #include <linux/of_net.h>
 #include <linux/regulator/consumer.h>
 
+#include "stmmac_platform.h"
+
 struct sunxi_priv_data {
 	int interface;
 	int clk_enabled;

drivers/net/ethernet/stmicro/stmmac/stmmac.h

···
 bool stmmac_eee_init(struct stmmac_priv *priv);
 
 #ifdef CONFIG_STMMAC_PLATFORM
-extern const struct stmmac_of_data meson6_dwmac_data;
-extern const struct stmmac_of_data sun7i_gmac_data;
-extern const struct stmmac_of_data stih4xx_dwmac_data;
-extern const struct stmmac_of_data stid127_dwmac_data;
-extern const struct stmmac_of_data socfpga_gmac_data;
 extern struct platform_driver stmmac_pltfr_driver;
 
 static inline int stmmac_register_platform(void)

drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c

···
 #include <linux/of.h>
 #include <linux/of_net.h>
 #include <linux/of_device.h>
+
 #include "stmmac.h"
+#include "stmmac_platform.h"
 
 static const struct of_device_id stmmac_dt_ids[] = {
 	/* SoC specific glue layers should come before generic bindings */

drivers/net/ethernet/stmicro/stmmac/stmmac_platform.h

···
+/*******************************************************************************
+  Copyright (C) 2007-2009  STMicroelectronics Ltd
+
+  This program is free software; you can redistribute it and/or modify it
+  under the terms and conditions of the GNU General Public License,
+  version 2, as published by the Free Software Foundation.
+
+  This program is distributed in the hope it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+  more details.
+
+  The full GNU General Public License is included in this distribution in
+  the file called "COPYING".
+
+  Author: Giuseppe Cavallaro <[e-mail]>
+*******************************************************************************/
+
+#ifndef __STMMAC_PLATFORM_H__
+#define __STMMAC_PLATFORM_H__
+
+extern const struct stmmac_of_data meson6_dwmac_data;
+extern const struct stmmac_of_data sun7i_gmac_data;
+extern const struct stmmac_of_data stih4xx_dwmac_data;
+extern const struct stmmac_of_data stid127_dwmac_data;
+extern const struct stmmac_of_data socfpga_gmac_data;
+
+#endif /* __STMMAC_PLATFORM_H__ */