add osmo_mgcpc_ep_ci_get_remote_rtp_info()

So far an mgcp_client user can get the RTP address+port information that
the MGW has returned upon a CRCX. Add this function to return the other
RTP end, i.e. address+port that the MGW was told to send RTP to.

This will be used to fix the MGCP in osmo-bsc, which so far mixes up the
two RTP ends and compares the MSC's RTP address+port with the MGW's one
and hence fails to skip unnecessary MDCX.

Change-Id: Ibb488925827d9dc0ccb1f8d6d84728745d086793
2 files changed