pcu: Ignore dummy rlcmac packets in f_ms_rx_pkt_ass_pacch

Allow ignoring for received dumy packets while waiting for a Pkt Ass on
PACCH. This fixes some tests failing sometimes due to race condition
where rlcmac packet is requested too quicky, after the PCU has received
the BSSGP packet we sent to it.

The function is splitted into an internal altestep + a wrap function
which is compatible with tests already using it.

Related: OS#4779
Change-Id: I0a10d3a7383d8534e9263864b4130a96392e6198
2 files changed