rtpproxy: proper iovec size for rtpproxy commands

- issue introduced with the last fix for timeout socket parameter
- reported by Laurent Schweizer
(cherry picked from commit 7c7e9f1051148887b7c5a578a9d09d66bf9586ce)

modules/rtpproxy/rtpproxy.c

@@ -2222,9 +2222,9 @@ force_rtp_proxy(struct sip_msg* msg, char* str1, char* str2, int offer, int forc
 				} else {
 					v[3].iov_len = 0;
 				}
-				if (opts.s.s[0] == 'U' && to_tag.len > 0) {
+				if (to_tag.len > 0) {
 					iovec_param_count = 18;
-					if (timeout_socket_str.len > 0) {
+					if (opts.s.s[0] == 'U' && timeout_socket_str.len > 0) {
 						iovec_param_count = 20;
 						STR2IOVEC(timeout_socket_str, v[19]);
 					}