tbf: Keep a set of used TFI and USF per PDCH

Currently is is rather expensive to get TFI and USF usage per PDCH,
because the TBFs need to be scanned to get that information.

This commit adds corresponding bit sets which get updated by the
attach_tbf/detach_tbf methods of the gprs_rlcmac_pdch class.

Sponsored-by: On-Waves ehf
3 files changed