osmo-trx: Add multi_arfcn support

2nd TRX arfcn is changed in defaults.conf because multi_arfcn requires
them to be alocated in steps of 4 starting from TRX0.

It is not enabled by default yet on B200 (it must use it to support
several TRX) because current host running osmo-gsm-tester is not
performant enough and cannot keep up with timers due to multi-arfcn CPU
overhead.

Change-Id: I096df82ad1f4cbb41dfbd6a78466a845f34be385
4 files changed