endpoint_fsm: add missing return in mgcp_pick_codec

The function mgcp_pick_codec is responsible to set the codec
information. In cases whee the codec type can not be determined
correctly it sets verb_info->codecs_len = 0, indicating to the caller
that no codocs are set. However, after that it does not return, it sets
an invalid codec anyway.

- Add missing return to keep the no-codec setting in case of error.

Change-Id: I8d1f8553357b6ad328ab1e5d4525fad0dd282a42

src/osmo-bsc/mgw_endpoint_fsm.c

@@ -739,6 +739,7 @@ void mgcp_pick_codec(struct mgcp_conn_peer *verb_info, const struct gsm_lchan *l
 			  "Unable to determine MGCP codec type for %s in chan-mode %s\n",
 			  gsm_lchant_name(lchan->type), gsm48_chan_mode_name(lchan->tch_mode));
 		verb_info->codecs_len = 0;
+		return;
 	}
 
 	verb_info->codecs[0] = codec;