usb: dwc3: gadget: set state to NOT_ATTACHED on disconnect_irq

whenever we get a Disconnect Interrupt, we should
make sure to update out udc state to NOT_ATTACHED,
otherwise sysfs will show wrong values.

Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 748b87b..12f4284 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2140,6 +2140,7 @@
 
 	dwc->gadget.speed = USB_SPEED_UNKNOWN;
 	dwc->setup_packet_pending = false;
+	usb_gadget_set_state(&dwc->gadget, USB_STATE_NOTATTACHED);
 }
 
 static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)