res_pjsip_sdp_rtp: Don't wait for ICE if not negotiated

If ICE support is enabled but not negotiated, the rtp->ice structure is
not being destroyed. This leads to Asterisk waiting for ICE to complete
instead of immediately starting the DTLS handshake, resulting in the
call leg having no RTP.

ASTERISK-28769 #close

Change-Id: I17c137546dc9ecfb9583c24dcf4c2ced8bbd7a27

res/res_pjsip_sdp_rtp.c

@@ -592,6 +592,7 @@ static void add_ice_to_stream(struct ast_sip_session *session, struct ast_sip_se
 	}
 
 	if (!session_media->remote_ice) {
+		ice->stop(session_media->rtp);
 		return;
 	}