BIT0: This is to control if a platform wants to enable VTd
based protection during boot.
BIT1: This is to control if a platform wants to keep VTd
enabled at ExitBootService.
The default configuration is BIT0:1, BIT1:0.
Cc: Star Zeng <star.zeng@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>