usb: dwc3: ep0: only change to ADDRESS if set_config() succeeds

In case we're switching back to USB_STATE_ADDRESS
from USB_STATE_CONFIGURED (if host sends
a set configuration command for configuration
zero), we should only switch if the request
is successfully processed by the gadget driver.
Reported-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/ep0.c

@@ -551,7 +551,7 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 
 	case USB_STATE_CONFIGURED:
 		ret = dwc3_ep0_delegate_req(dwc, ctrl);
-		if (!cfg)
+		if (!cfg && !ret)
 			usb_gadget_set_state(&dwc->gadget,
 					USB_STATE_ADDRESS);
 		break;