fix segfault introduced by recent segfault fix

This recently merged patch introduced a new bad segfault in bsc_compl_l3() by
dereferencing conn->sccp.msc before it was set to the actual msc pointer:

commit 6281d4f8692729dc0022ea7a6a2068972d58e9b6
"fix crashes due to OSMO_ASSERT(conn->lchan)"
Change-Id Id681dfb0ad654bdb4b71805d1ad4f39a8bf6bbd1

Fix that by moving the new checks back further down in bsc_compl_l3(), to where
conn->sccp.msc actually points at the msc.

Change-Id: Ic5832da7c58fce583caa504a90f18c334fc234f2
1 file changed