fsm: fix state_chg(): pass microseconds to osmo_timer_schedule()

As was demonstrated in [1], osmo_fsm_inst_state_chg_ms() is broken.
The problem is in state_chg(): this function is passing *milli*seconds
to osmo_timer_schedule(), while it expects *micro*seconds.

Change-Id: Ib0b6c3bdb56e4279df9e5ba7db16841645c452aa
Related: [1] I5a35730a8448292b075aefafed897353678250f9
Fixes: I35b330e460e80bb67376c77e997e464439ac5397
Fixes: OS#5622
diff --git a/tests/fsm/fsm_test.c b/tests/fsm/fsm_test.c
index ec31dd2..6fa0ae7 100644
--- a/tests/fsm/fsm_test.c
+++ b/tests/fsm/fsm_test.c
@@ -441,15 +441,13 @@
 	OSMO_ASSERT(timeout_fired == -1);
 
 	fake_time_passes(0, 350000); /* +350ms, 1s 100ms total */
-	/* OSMO_ASSERT(timeout_fired == -1); */
-
-	/* FIXME: the timeout expires here, earlier than expected */
+	OSMO_ASSERT(timeout_fired == -1);
 
 	fake_time_passes(0, 200000); /* +200ms, 1s 300ms total */
-	/* OSMO_ASSERT(timeout_fired == -1); */
+	OSMO_ASSERT(timeout_fired == -1);
 
 	fake_time_passes(0, 37000); /* +37ms, 1s 337ms total */
-	/* OSMO_ASSERT(timeout_fired == 4242); */
+	OSMO_ASSERT(timeout_fired == 4242);
 
 	osmo_fsm_inst_term(fi, OSMO_FSM_TERM_REQUEST, NULL);