osmo-bts-trx: reset BTS GSM time on clock (re)start
trx_sched_clock_started() is called when the transceiver is powered on, e.g. after an A-bis link re-establishment, which in ttcn3-bts-test happens once per testcase. The transceiver restarts its TDMA frame number from ~0, but we only reset the per-TRX clock state (tcs), leaving bts->gsm_time.fn at the previous epoch's value.
As a result the first (low) FN reported by the transceiver is mistaken for a huge backwards jump, e.g.:
l1sap.c:628 Invalid condition detected: Frame difference is 102-10386=2705364 > 1!
Reset bts->gsm_time to FN 0 here so each clock epoch starts clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Change-Id: Id8da126e460d3846a3be5bdb271553457fdd0590
