Add NULL check to the return buffers from GetFmpHandleBufferByType(). Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Hao A Wu <Hao.a.wu@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Star Zeng <star.zeng@intel.com> Reviewed-by: Hao A Wu <Hao.a.wu@intel.com>