libnetwork/iptables: un-export FirewalldInit

It's only used internally, and it was last used in commit:
https://github.com/moby/libnetwork/commit/0220b06cd6e0048adef13aba5cba3fea8be7fede

But moved into the iptables package in this commit:
https://github.com/moby/libnetwork/commit/998f3ce22c641b33f062d111f043e92495e3804c

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

libnetwork/iptables/firewalld.go

@@ -65,8 +65,8 @@ var (
 	onReloaded       []*func() // callbacks when Firewalld has been reloaded
 )
 
-// FirewalldInit initializes firewalld management code.
-func FirewalldInit() error {
+// firewalldInit initializes firewalld management code.
+func firewalldInit() error {
 	var err error
 
 	if connection, err = newConnection(); err != nil {

libnetwork/iptables/firewalld_test.go

@@ -13,7 +13,7 @@ func TestFirewalldInit(t *testing.T) {
 	if !checkRunning() {
 		t.Skip("firewalld is not running")
 	}
-	if err := FirewalldInit(); err != nil {
+	if err := firewalldInit(); err != nil {
 		t.Fatal(err)
 	}
 }

libnetwork/iptables/iptables.go

@@ -125,7 +125,7 @@ func initFirewalld() {
 		log.G(context.TODO()).Info("skipping firewalld management for rootless mode")
 		return
 	}
-	if err := FirewalldInit(); err != nil {
+	if err := firewalldInit(); err != nil {
 		log.G(context.TODO()).WithError(err).Debugf("unable to initialize firewalld; using raw iptables instead")
 	}
 }