usb: musb: omap2430: fix compile warning

fix the following compile warning:

drivers/usb/musb/omap2430.c: In function 'musb_otg_notifier_work':
drivers/usb/musb/omap2430.c:279:3: warning: 'return' with a value, in
	function returning void
drivers/usb/musb/omap2430.c:282:2: warning: 'return' with a value, in
	function returning void

Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/musb/omap2430.c b/drivers/usb/musb/omap2430.c
index fd5dd46..c24dc26 100644
--- a/drivers/usb/musb/omap2430.c
+++ b/drivers/usb/musb/omap2430.c
@@ -283,10 +283,7 @@
 		break;
 	default:
 		dev_dbg(musb->controller, "ID float\n");
-		return NOTIFY_DONE;
 	}
-
-	return NOTIFY_OK;
 }
 
 static int omap2430_musb_init(struct musb *musb)