Changes

Don't crash on loc req with disabled SMLC

Fix that OsmoBSC crashes when receiving a location request from the MSC
while the SMLC is disabled. With this patch, a system failure is
reported to the MSC and the following error message is logged:

SUBSCR_CONN(msc0-conn1_subscr-IMSI-001019935148766)[0x59d28e261f60]{ACTIVE}: Lb link to SMLC is not ready (no RESET-ACK), cannot send BSSMAP-LE PERFORM LOCATION REQUEST with BSSLAP TA Layer3

Suggested-by: Harald Welte <laforge@osmocom.org>
Related: SYS#7714
Related: osmo-ttcn3-hacks I1cd7a7658b21d3eb04443a15ffd5ddf09b466af5
Change-Id: Ie8a66f9decf9fff602f7fecfb71a78fab900066f
(cherry picked from commit ea1764f9f474536d96dc8b95bc5aab1261cfefbe)