UefiCpuPkg: support single EFI_PEI_CORE_FV_LOCATION_PPI in PpiList

UefiCpuPkg: support single EFI_PEI_CORE_FV_LOCATION_PPI in PpiList

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2153

Current logic will skip searching EFI_PEI_CORE_FV_LOCATION_PPI when the
PPI in PpiList having EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST flag,
but platform may pass single PPI in PpiList that should be supported.

Changed the logic to verify PpiList first before checking
EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST flag.

Test: Verified both single EFI_PEI_CORE_FV_LOCATION_PPI and multiple
      PPIs in PpiList cases and both can boot with the PeiCore
      specified by EFI_PEI_CORE_FV_LOCATION_PPI.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>