Create an SEV-ES workarea PCD. This PCD will be used for BSP communication
during SEC and for AP startup during PEI and DXE phases, the latter is the
reason for creating it in the UefiCpuPkg.
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>