Fix gosimple

Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>

libnetwork/default_gateway.go

@@ -181,10 +181,8 @@ func (c *controller) defaultGwNetwork() (Network, error) {
 	defer func() { <-procGwNetwork }()
 
 	n, err := c.NetworkByName(libnGWNetwork)
-	if err != nil {
-		if _, ok := err.(types.NotFoundError); ok {
-			n, err = c.createGWNetwork()
-		}
+	if _, ok := err.(types.NotFoundError); ok {
+		n, err = c.createGWNetwork()
 	}
 	return n, err
 }