oc2gbts_mgr: use osmo_init_logging2() instead of osmo_init_logging()
oc2gbts_mgr: use osmo_init_logging2() instead of osmo_init_logging()

The function osmo_init_logging() is deprecated, lets use
osmo_init_logging2() as suggested.

Change-Id: Iebc80cd1f77f10a879d4536d788377f522dd853f

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