REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2594
Add null version of RpmcLib instance. The full version should be provided
by platform which supports RPMC device.
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Nishant C Mistry <nishant.c.mistry@intel.com>
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Jian J Wang