usb: gadget: goku_udc: let udc-core manage gadget->dev

By simply setting a flag, we can drop some
boilerplate code.

Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/gadget/goku_udc.h b/drivers/usb/gadget/goku_udc.h
index b4470d2..86d2ada 100644
--- a/drivers/usb/gadget/goku_udc.h
+++ b/drivers/usb/gadget/goku_udc.h
@@ -250,8 +250,7 @@
 					got_region:1,
 					req_config:1,
 					configured:1,
-					enabled:1,
-					registered:1;
+					enabled:1;
 
 	/* pci state used to access those endpoints */
 	struct pci_dev			*pdev;