core: osmo_tdef_fsm_inst_state_chg(): allow millisecond precision

This API predates commit 7b74551b9, which added support for millisecond
granularity to osmo_fsm.  Let's do the same for the tdef FSM wrapper
API, allowing the millisecond precision without rounding-up to seconds.

Of course, this patch changes behavior of the existing API, but having
more precise state timeouts is not going to make the API user
experience worse.

The old behavior of using seconds is for kept for:

* OSMO_TDEF_CUSTOM -- still treated as if it was OSMO_TDEF_S.
* \param[in] default_timeout -- still expected to be in seconds.

Change-Id: I4c4ee89e7e32e86f74cd215f5cbfa44ace5426c1
Related: 7b74551b9 "fsm: Allow millisecond granularity in osmo_fsm built-in timer"
diff --git a/TODO-RELEASE b/TODO-RELEASE
index 9f5240f..41bd5d8 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -11,6 +11,7 @@
 core      ADD       osmo_sock_multiaddr_get_ip_and_port(), osmo_multiaddr_ip_and_port_snprintf(), osmo_sock_multiaddr_get_name_buf()
 core      ADD       osmo_sock_sctp_get_peer_addr_info()
 core      ADD       gsmtap_inst_fd2() core, DEPRECATE gsmtap_inst_fd()
+core		behavior change		osmo_tdef_fsm_inst_state_chg(): allow millisecond precision
 isdn		ABI change		add states and flags for external T200 handling
 gsm		ABI change		add T200 timer states to lapdm_datalink
 gsm		ABI change		add UI queue to struct lapdm_datalink