usb: gadget: configfs: 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/configfs.c

@@ -1450,6 +1450,7 @@ static const struct usb_gadget_driver configfs_driver_template = {
 	.unbind         = configfs_composite_unbind,
 
 	.setup          = composite_setup,
+	.reset          = composite_disconnect,
 	.disconnect     = composite_disconnect,
 
 	.max_speed	= USB_SPEED_SUPER,