[CONNECTOR]: Return proper error code in cn_call_callback()

Error code should be set to EINVAL instead of ENODEV if !queue_work().
There's another call of queue_work() which may set err to EINVAL.

Signed-off-by: Li Zefan <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/connector/connector.c

···
 				if (queue_work(dev->cbdev->cn_queue,
 							&__cbq->work))
 					err = 0;
+				else
+					err = -EINVAL;
 			} else {
 				struct cn_callback_data *d;