libnetwork/drivers/bridge: fix non-constant format string in call (go…

…vet)

    libnetwork/drivers/bridge/setup_ip_tables_linux.go:385:23: printf: non-constant format string in call to fmt.Errorf (govet)
                    return fmt.Errorf(msg)
                                      ^

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 068c1bf)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

libnetwork/drivers/bridge/setup_ip_tables_linux.go

@@ -382,7 +382,7 @@ func setINC(version iptables.IPVersion, iface string, enable bool) error {
 						log.G(context.TODO()).Warnf("Failed to rollback iptables rule after failure (%v): %v", err, err2)
 					}
 				}
-				return fmt.Errorf(msg)
+				return errors.New(msg)
 			}
 			log.G(context.TODO()).Warn(msg)
 		}