chan_sip.c: Suppress T.38 SDP c= line if addr is the same.

Use the correct comparison function since we only care if the address
without the port is the same.

Change-Id: Ibf6c485f843a1be6dee58a47b33d81a7a8cbe3b0

channels/chan_sip.c

@@ -13447,7 +13447,7 @@ static enum sip_result add_sdp(struct sip_request *resp, struct sip_pvt *p, int
 		ast_str_append(&m_modem, 0, "m=image %d udptl t38\r\n", ast_sockaddr_port(&udptldest));
-		if (ast_sockaddr_cmp(&udptldest, &dest)) {
+		if (ast_sockaddr_cmp_addr(&udptldest, &dest)) {
 			ast_str_append(&m_modem, 0, "c=IN %s %s\r\n",
 					(ast_sockaddr_is_ipv6(&udptldest) && !ast_sockaddr_is_ipv4_mapped(&udptldest)) ?
 					"IP6" : "IP4", ast_sockaddr_stringify_addr_remote(&udptldest));