usb: convert drivers/usb/* to use module_platform_driver()

This patch converts the drivers in drivers/usb/* to use the
module_platform_driver() macro which makes the code smaller and a bit
simpler.

Cc: Felipe Balbi <balbi@ti.com>
Cc: Li Yang <leoli@freescale.com>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/dwc3/dwc3-omap.c b/drivers/usb/dwc3/dwc3-omap.c
index 062552b..4e27d5b 100644
--- a/drivers/usb/dwc3/dwc3-omap.c
+++ b/drivers/usb/dwc3/dwc3-omap.c
@@ -384,18 +384,8 @@
 	},
 };
 
+module_platform_driver(dwc3_omap_driver);
+
 MODULE_AUTHOR("Felipe Balbi <balbi@ti.com>");
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_DESCRIPTION("DesignWare USB3 OMAP Glue Layer");
-
-static int __devinit dwc3_omap_init(void)
-{
-	return platform_driver_register(&dwc3_omap_driver);
-}
-module_init(dwc3_omap_init);
-
-static void __exit dwc3_omap_exit(void)
-{
-	platform_driver_unregister(&dwc3_omap_driver);
-}
-module_exit(dwc3_omap_exit);