USB: cdc-wdm: sanitize error returns

wdm_flush() returns unsanitized USB error codes.
They must be cleaned up to before being anded to user space
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/class/cdc-wdm.c

@@ -531,7 +531,7 @@ static int wdm_flush(struct file *file, fl_owner_t id)
 		dev_err(&desc->intf->dev, "Error in flush path: %d\n",
 			desc->werr);
 
-	return desc->werr;
+	return usb_translate_errors(desc->werr);
 }
 
 static unsigned int wdm_poll(struct file *file, struct poll_table_struct *wait)