Changes

rsl: rsl_handle_chan_mod_ie(): set lchan->csd_mode for NT CSD

In commit 66eae187, I skipped assigning LCHAN_CSD_M_NT (0) to
lchan->csd_mode for non-transparent channel modes.  I assumed that
the entire gsm_lchan struct was zero-initialized during activation
or release procedures, but this assumption was incorrect.

In fact, some lchan fields are initialized during activation, while
others are initialized during release.  Specifically, lchan->csd_mode
is zero-initialized when the process starts, and then updated only
for transparent mode requests.  For non-transparent mode requests,
this field is not updated, meaning it retains its previous value.

This bug caused incorrect E1/E2/E3 bit settings and missing GSMTAP
RLP output for channels that were previously used for transparent
CSD calls.  This patch is fixing it.

Change-Id: I793ab4dc25fa852eade6f7a3b67ae961ceb7a093
Fixes: 66eae187 "rsl: rsl_handle_chan_mod_ie(): set lchan->csd_mode"
Related: OS#1572, OS#6579