Platform/Intel: Add VmgExitLib to required DSC files

Any DSC file that uses the UefiCpuPkg MpInitLib or CpuExeptionHandlerLib
libraries, now requires the VmgExitLib library. Update the DSC files to
include the VmgExitLib NULL library implementation.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>