usb: musb: gadget: don't call ->disconnect() on exit

that has already being done by udc-core.c. It's
unnecessary and might cause issues with some gadget
drivers.

Tested: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/musb/musb_gadget.c

@@ -1999,10 +1999,6 @@ static void stop_activity(struct musb *musb, struct usb_gadget_driver *driver)
 					nuke(&hw_ep->ep_out, -ESHUTDOWN);
 			}
 		}
-
-		spin_unlock(&musb->lock);
-		driver->disconnect(&musb->g);
-		spin_lock(&musb->lock);
 	}
 }