IntelSiliconPkg/dec: Add VTd policy PCD
IntelSiliconPkg/dec: Add VTd policy PCD

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 <5c6bb72efe464613af94e84c05522a361b23844a@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiewen Yao <364a90bfebd1f362ebb7b48e4bf8ec010adef203@intel.com>
Reviewed-by: Star Zeng <5c6bb72efe464613af94e84c05522a361b23844a@intel.com>

MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2