ptp_pch: Move 'pch_*()' prototypes to shared header

Fixes the following W=1 kernel build warning(s):

drivers/ptp/ptp_pch.c:193:6: warning: no previous prototype for ‘pch_ch_control_write’ [-Wmissing-prototypes]
drivers/ptp/ptp_pch.c:201:5: warning: no previous prototype for ‘pch_ch_event_read’ [-Wmissing-prototypes]
drivers/ptp/ptp_pch.c:212:6: warning: no previous prototype for ‘pch_ch_event_write’ [-Wmissing-prototypes]
drivers/ptp/ptp_pch.c:220:5: warning: no previous prototype for ‘pch_src_uuid_lo_read’ [-Wmissing-prototypes]
drivers/ptp/ptp_pch.c:231:5: warning: no previous prototype for ‘pch_src_uuid_hi_read’ [-Wmissing-prototypes]
drivers/ptp/ptp_pch.c:242:5: warning: no previous prototype for ‘pch_rx_snap_read’ [-Wmissing-prototypes]
drivers/ptp/ptp_pch.c:259:5: warning: no previous prototype for ‘pch_tx_snap_read’ [-Wmissing-prototypes]
drivers/ptp/ptp_pch.c:300:5: warning: no previous prototype for ‘pch_set_station_address’ [-Wmissing-prototypes]

Cc: Richard Cochran <[e-mail]> (maintainer:PTP HARDWARE CLOCK SUPPORT)
Cc: "David S. Miller" <[e-mail]>
Cc: Jakub Kicinski <[e-mail]>
Cc: Flavio Suligoi <[e-mail]>
Cc: [e-mail]
Signed-off-by: Lee Jones <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe.h

···
 void pch_gbe_free_rx_resources(struct pch_gbe_adapter *adapter,
 			       struct pch_gbe_rx_ring *rx_ring);
 void pch_gbe_update_stats(struct pch_gbe_adapter *adapter);
-void pch_ch_control_write(struct pci_dev *pdev, u32 val);
-u32 pch_ch_event_read(struct pci_dev *pdev);
-void pch_ch_event_write(struct pci_dev *pdev, u32 val);
-u32 pch_src_uuid_lo_read(struct pci_dev *pdev);
-u32 pch_src_uuid_hi_read(struct pci_dev *pdev);
-u64 pch_rx_snap_read(struct pci_dev *pdev);
-u64 pch_tx_snap_read(struct pci_dev *pdev);
-int pch_set_station_address(u8 *addr, struct pci_dev *pdev);
 
 /* pch_gbe_param.c */
 void pch_gbe_check_options(struct pch_gbe_adapter *adapter);

drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c

···
 #include <linux/module.h>
 #include <linux/net_tstamp.h>
 #include <linux/ptp_classify.h>
+#include <linux/ptp_pch.h>
 #include <linux/gpio.h>
 
 #define DRV_VERSION     "1.01"

drivers/ptp/ptp_pch.c

···
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/ptp_clock_kernel.h>
+#include <linux/ptp_pch.h>
 #include <linux/slab.h>
 
 #define STATION_ADDR_LEN	20

include/linux/ptp_pch.h

···
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * PTP PCH
+ *
+ * Copyright 2019 Linaro Ltd.
+ *
+ * Author Lee Jones <[e-mail]>
+ */
+
+#ifndef _PTP_PCH_H_
+#define _PTP_PCH_H_
+
+void pch_ch_control_write(struct pci_dev *pdev, u32 val);
+u32  pch_ch_event_read(struct pci_dev *pdev);
+void pch_ch_event_write(struct pci_dev *pdev, u32 val);
+u32  pch_src_uuid_lo_read(struct pci_dev *pdev);
+u32  pch_src_uuid_hi_read(struct pci_dev *pdev);
+u64  pch_rx_snap_read(struct pci_dev *pdev);
+u64  pch_tx_snap_read(struct pci_dev *pdev);
+int  pch_set_station_address(u8 *addr, struct pci_dev *pdev);
+
+#endif /* _PTP_PCH_H_ */