usb: dwc3: gadget: Fix incorrect UDC state after manual deconfiguration

The UDC state in sysfs (/sys/class/udc/<udc>/state) should accurately
reflect the current state of the USB Device Controller.

Currently, the UDC state is not handled consistently during gadget
disconnection. While the disconnect interrupt path correctly sets the
state to "not-attached", manual deconfiguration leaves the state in
"configured", misrepresenting the actual situation.

This commit ensures consistent UDC state handling by setting the state to
"not-attached" after manual deconfiguration. This accurately reflects the
UDC's state and provides a consistent behavior regardless of the
disconnection method.

Signed-off-by: Roy Luo <royluo@google.com>
Reviewed-by: André Draszik <andre.draszik@linaro.org>
Tested-by: André Draszik <andre.draszik@linaro.org>
Link: https://lore.kernel.org/r/20241223042536.1465299-1-royluo@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/gadget.c

@@ -2740,6 +2740,8 @@ static int dwc3_gadget_soft_disconnect(struct dwc3 *dwc)
 	__dwc3_gadget_stop(dwc);
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
+	usb_gadget_set_state(dwc->gadget, USB_STATE_NOTATTACHED);
+
 	return ret;
 }