After sending of NM_MT_IPACC_RSL_CONNECT message, we start a timer,
and stop it on receipt of NM_MT_IPACC_RSL_CONNECT_{ACK,NACK}. When
running a multi-trx setup, one can see the following warnings:
DRSL NOTICE abis_nm.c:2852 (bts=0,trx=1) RSL connection request timed out
DRSL NOTICE abis_nm.c:2852 (bts=0,trx=2) RSL connection request timed out
even despite NM_MT_IPACC_RSL_CONNECT is actually being acknowledged.
The problem is in abis_nm_rx_ipacc(): we cannot just use sign_link->trx,
because the message itself was received over the OML link, so this
pointer always gives us C0/TRX0. Instead, we must find a TRX by its
number from the FOH header using gsm_bts_trx_by_nr().
Change-Id: Ib4b9a198da11c88a51cfa78ffb7e7235a6365ef4
a1d175ab66