csd_v110: handle TCH/F14.4

Thanks to the work done by Mychaela (see the related Change-IDs), we
can finally implement handling of TCH/F14.4 (both T and NT modes) for
osmo-bts-trx and osmo-bts-virtual.

This channel mode is special in a way that it employs a different
rate adaptation function RAA' (defined in 3GPP TS 48.020 chapter 11),
which converts between between 290-bit blocks used on Um and Abis-E1
interfaces (E-TRAU frames on the latter) and A-TRAU frames spoken
over the A interface.

The result of function RAA' in the Uplink direction is 320 bits,
which is equal to 4 x 80-bit V.110 frames, but actually carrying
8 x 36-bit packed frames.  These 320 bits are then fed to the RA2
function, like we do for other CSD channel modes.

Change-Id: I3c3bef0bd2f72b8381597b5699e2060165b702a0
Depends: libosmo-abis.git I11fc1529f5be88fa778c7e05cb11eef58a389d40
Depends: libosmo-abis.git I1347a25ce97d5022502ee9112caded66315b09a4
Related: OS#6167
---
M TODO-RELEASE
M src/common/bts.c
M src/common/csd_v110.c
M src/osmo-bts-trx/main.c
M src/osmo-bts-virtual/main.c
M tests/csd/csd_test.c
M tests/csd/csd_test.err
7 files changed, 59 insertions(+), 11 deletions(-)