Fix memory corruption when switching NFC off

This patch ensures that memory buffer used for LLC context
is not accessed anymore after it is released.

The "bad" memory access used to happen previously
from the following routines:

- LLC Ack timeout callback
- DAL reader thread.

Change-Id: Ic8470fef58b95f0e407ebadca93182de0c0cf793
Orig-Change-Id: I7dc87dae7026382625eb2e0482cf1d5447e2b483
Signed-off-by: Sebastian Niciarz <sebastian.niciarz@intel.com>
Signed-off-by: Olivier Deprez <olivier.deprez@intel.com>
Reviewed-on: http://android.intel.com:8080/116130
Reviewed-by: Rebraca, DejanX <dejanx.rebraca@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: Lestienne, ChristopheX <christophex.lestienne@intel.com>
Tested-by: buildbot <buildbot@intel.com>
Signed-off-by: Jian Luo <jian.luo@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 118935