tbf: Refactor parts of extract_tlli into set_tlli_from_ul

Currently gprs_rlcmac_tbf::extract_tlli takes care of decoding and
the TBF update. These are really different things and doing the
decoding in extract_tlli makes EGPRS support more complex.

This commit moves the TBF state related part into a new method
gprs_rlcmac_tbf::set_tlli_from_ul.

Sponsored-by: On-Waves ehf
3 files changed