staging: mt7621-pci-phy: use builtin_platform_driver()

Macro builtin_platform_driver can be used for builtin drivers
that don't do anything in driver init. So, use the macro
builtin_platform_driver and remove some boilerplate code.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20200321133624.31388-3-sergio.paracuellos@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-pci-phy/pci-mt7621-phy.c

@@ -361,12 +361,7 @@ static struct platform_driver mt7621_pci_phy_driver = {
 	},
 };
 
-static int __init mt7621_pci_phy_drv_init(void)
-{
-	return platform_driver_register(&mt7621_pci_phy_driver);
-}
-
-module_init(mt7621_pci_phy_drv_init);
+builtin_platform_driver(mt7621_pci_phy_driver);
 
 MODULE_AUTHOR("Sergio Paracuellos <sergio.paracuellos@gmail.com>");
 MODULE_DESCRIPTION("MediaTek MT7621 PCIe PHY driver");