Protect pktlog funcitonality under given mutex to avoid possible
race condition between pktlog_release/pktlog_open and pktlogmod_exit.
Also call pktlogmod_exit before calling wdi_event_detach to avoid
accessing freed memory in pktlog release.
Change-Id: I5ca4b304d0f4dc1af289daa167958d5b773d9a6e
CRs-Fixed: 2578623