[VAMOS] rsl_lchan_lookup(): use ABIS_RSL_CHAN_NR_CBITS_* macros
[VAMOS] rsl_lchan_lookup(): use ABIS_RSL_CHAN_NR_CBITS_* macros

Change-Id: Iec3250e3a59f8d428d7e7be2ceb71f7086a68e7b
Related: SYS#4895, OS#4941

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