usb: gadget: dbgp: add reset API at usb_gadget_driver

Add reset API at usb_gadget_driver, it calls disconnect handler currently,
but may do different things in future.
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/legacy/dbgp.c

@@ -410,6 +410,7 @@ static __refdata struct usb_gadget_driver dbgp_driver = {
 	.bind = dbgp_bind,
 	.unbind = dbgp_unbind,
 	.setup = dbgp_setup,
+	.reset = dbgp_disconnect,
 	.disconnect = dbgp_disconnect,
 	.driver	= {
 		.owner = THIS_MODULE,