compl l3: populate conn's bsc subscr from MI

Set conn->bsub as indicated by the Mobile Identity. Now the
'log_set_context(LOG_CTX_BSC_SUBSCR, conn->bsub);' becomes useful.

Upcoming patch to support Perform Location Request will use the subscriber to
retrieve an already established conn via the bsub.

Drop fixme in gscon_fsm_init(), MI now extracted and id updated.

Change-Id: I00d4c7e8284b745368a432a7ec176aa99f79db47
2 files changed