net/ethernet: xgmac don't set .driver twice

Cleanup the .driver setup to just do it once, to avoid
the following sparse warning:

drivers/net/ethernet/calxeda/xgmac.c:1914:10: warning: Initializer entry defined twice
drivers/net/ethernet/calxeda/xgmac.c:1920:10:   also defined here
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

drivers/net/ethernet/calxeda/xgmac.c

@@ -1914,10 +1914,10 @@ static struct platform_driver xgmac_driver = {
 	.driver = {
 		.name = "calxedaxgmac",
 		.of_match_table = xgmac_of_match,
+		.pm = &xgmac_pm_ops,
 	},
 	.probe = xgmac_probe,
 	.remove = xgmac_remove,
-	.driver.pm = &xgmac_pm_ops,
 };
 
 module_platform_driver(xgmac_driver);