WhitleyOpenBoardPkg: Support FSP 2.3 FSP_NON_VOLATILE_STORAGE_HOB2.

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3678



Implementation should search FSP_NON_VOLATILE_STORAGE_HOB2 firstly
and only search FSP_NON_VOLATILE_STORAGE_HOB when former one is not found.

Also added PeiGetLargeVariable () to support the scenarios where the
variable data size is bigger than a single variable size limit.

Cc: Isaac Oram <isaac.w.oram@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Signed-off-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
Reviewed-by: Isaac Oram <isaac.w.oram@intel.com>