mod_sofia: My iLBC changes caused a problem with fmtp was empty, this should fix it

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@16928 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/endpoints/mod_sofia/sofia_glue.c

@@ -3546,8 +3546,8 @@ uint8_t sofia_glue_negotiate_sdp(switch_core_session_t *session, sdp_session_t *
 				}
 
 				if (!strcasecmp((char *) rm_encoding, "ilbc")) {
-					char *mode = strstr(map->rm_fmtp, "mode=");
-					if (mode && (mode + 5)) {
+					char *mode = NULL;
+					if (map->rm_fmtp && (mode = strstr(map->rm_fmtp, "mode=")) && (mode + 5)) {
 						codec_ms = atoi(mode + 5);
 					}
 					if (!codec_ms) {