net: macb: Perform zynqmp dynamic configuration only for SGMII interface

In zynqmp platforms where firmware supports dynamic SGMII configuration
but has other non-SGMII ethernet devices, it fails them with no packets
received at the RX interface.

To fix this behaviour perform SGMII dynamic configuration only
for the SGMII phy interface.

Fixes: 32cee7818111 ("net: macb: Add zynqmp SGMII dynamic configuration support")
Signed-off-by: Radhey Shyam Pandey <[e-mail]>
Reviewed-by: Jiri Pirko <[e-mail]>
Reported-by: Michal Simek <[e-mail]>
Tested-by: Michal Simek <[e-mail]>
Reviewed-by: Claudiu Beznea <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/cadence/macb_main.c

···
 		if (ret)
 			return dev_err_probe(&pdev->dev, ret,
 					     "failed to init SGMII PHY\n");
-	}
 
-	ret = zynqmp_pm_is_function_supported(PM_IOCTL, IOCTL_SET_GEM_CONFIG);
-	if (!ret) {
-		u32 pm_info[2];
+		ret = zynqmp_pm_is_function_supported(PM_IOCTL, IOCTL_SET_GEM_CONFIG);
+		if (!ret) {
+			u32 pm_info[2];
 
-		ret = of_property_read_u32_array(pdev->dev.of_node, "power-domains",
-						 pm_info, ARRAY_SIZE(pm_info));
-		if (ret) {
-			dev_err(&pdev->dev, "Failed to read power management information\n");
-			goto err_out_phy_exit;
+			ret = of_property_read_u32_array(pdev->dev.of_node, "power-domains",
+							 pm_info, ARRAY_SIZE(pm_info));
+			if (ret) {
+				dev_err(&pdev->dev, "Failed to read power management information\n");
+				goto err_out_phy_exit;
+			}
+			ret = zynqmp_pm_set_gem_config(pm_info[1], GEM_CONFIG_FIXED, 0);
+			if (ret)
+				goto err_out_phy_exit;
+
+			ret = zynqmp_pm_set_gem_config(pm_info[1], GEM_CONFIG_SGMII_MODE, 1);
+			if (ret)
+				goto err_out_phy_exit;
 		}
-		ret = zynqmp_pm_set_gem_config(pm_info[1], GEM_CONFIG_FIXED, 0);
-		if (ret)
-			goto err_out_phy_exit;
 
-		ret = zynqmp_pm_set_gem_config(pm_info[1], GEM_CONFIG_SGMII_MODE, 1);
-		if (ret)
-			goto err_out_phy_exit;
 	}
 
 	/* Fully reset controller at hardware level if mapped in device tree */