UefiCpuPkg/MpInitLib: Add CPU MP data flag to indicate if SEV-ES is enabled

UefiCpuPkg/MpInitLib: Add CPU MP data flag to indicate if SEV-ES is enabled

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198

When starting APs in an SMP configuration, the AP needs to know if it is
running as an SEV-ES guest in order to assign a GHCB page.

Add a field to the CPU_MP_DATA structure that will indicate if SEV-ES is
enabled. This new field is set during MP library initialization with the
PCD value PcdSevEsIsEnabled. This flag can then be used to determine if
SEV-ES is enabled.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>