L1SAP: clarify debug messages in rach_pass_filter()
L1SAP: clarify debug messages in rach_pass_filter()

RACH stands for Random Access CHannel, while in rach_pass_filter()
we're dealing with Access Bursts, that may be received on other
logical channels too (e.g. PTCCH, PDTCH or any other).

Change-Id: I1e5ca9930ab491a6916c972865154d54530cbf51

osmocom/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts