Added PlatformNotification to ACPI 5.0 PCCT structure.

(Sync patch r16452 from main trunk.)

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Samer El-Haj-Mahmoud <elhaj@hp.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

git-svn-id: svn://svn.code.sf.net/p/edk2/code/branches/UDK2014.SP1/MdePkg@16463 6f19259b-4bc3-4df7-8a09-765794883524