ms: restructure the va code to add rach support

This commit adds support for rach bursts to the viterbi equalizer, which
is currently only being used by the ms side, so the equalizer can be used
by the osmo-trx network side, too. The difference is that rach bursts are
shorter than any other burst type (due to unknown TA) and start with
diffrent tail bits.

This drops the multiversioning which was only working for x86 anyway because
it can't be combined with no_ubsan.

Change-Id: I4a5cedc8c9a3289c75ce7b914eac286e601ebed0
---
M Transceiver52M/grgsm_vitac/constants.h
M Transceiver52M/grgsm_vitac/grgsm_vitac.cpp
M Transceiver52M/grgsm_vitac/grgsm_vitac.h
M Transceiver52M/ms/ms_rx_lower.cpp
M Transceiver52M/ms/ms_upper.cpp
5 files changed, 131 insertions(+), 96 deletions(-)