usb: musb: Remove usb_disable() check in module_init()

Removing the check to usb_disable() before registering the platform
driver allows to build this driver when !USB && USB_GADGET, to be
used in gadget-only mode.

Also, use module_platform_driver() to register the platform driver.
Signed-off-by: NEzequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_core.c

@@ -2325,19 +2325,4 @@ static struct platform_driver musb_driver = {
 	.shutdown	= musb_shutdown,
 };
 
-/*-------------------------------------------------------------------------*/
-
-static int __init musb_init(void)
-{
-	if (usb_disabled())
-		return 0;
-
-	return platform_driver_register(&musb_driver);
-}
-module_init(musb_init);
-
-static void __exit musb_cleanup(void)
-{
-	platform_driver_unregister(&musb_driver);
-}
-module_exit(musb_cleanup);
+module_platform_driver(musb_driver);