mei: return error on notification request to a disconnected client

Request for a notification from a disconnected client will be ignored
silently by the FW but the caller should know that the operation hasn't
succeeded.
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/client.c

@@ -1331,6 +1331,9 @@ int mei_cl_notify_request(struct mei_cl *cl,
 		return -EOPNOTSUPP;
 	}
 
+	if (!mei_cl_is_connected(cl))
+		return -ENODEV;
+
 	rets = pm_runtime_get(dev->dev);
 	if (rets < 0 && rets != -EINPROGRESS) {
 		pm_runtime_put_noidle(dev->dev);