Fix switch_split_user_domain handling of sips: URLs

In commit 7efeabbd Anthony fixed the
handling of sip:example.com and sips:example.com URLs, however he
introduced a regression causing URLs starting with 's' to be parsed
incorrectly.

In commit 7d2456ea Brian fixed the
regression, but introduced a regression causing sips:example.com URLs
to be handled incorrectly.

src/switch_utils.c

@@ -3112,7 +3112,8 @@ SWITCH_DECLARE(int) switch_split_user_domain(char *in, char **user, char **domai
 
 	if (!strncasecmp(in, "sip", 3)) {
 		in += 3;
-		while(*in == ':') in++;
+		if (*in == 's') in++;
+		if (*in == ':') in++;
 	}
 
 	u = in;