Address the potential system TPL does not been restore.

This patch make sure the TPL been raised and restored in pair.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Deric Cole <Deric_Cole@phoenix.com>
Reviewed-by: Elvin Li <elvin.li@intel.com>


git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16556 6f19259b-4bc3-4df7-8a09-765794883524