1. Fix TOCTOU issue in VariableSmm, FtwSmm, FpdtSmm, SmmCorePerformance SMM handler. For VariableSmm, pre-allocate a mVariableBufferPayload buffer with mVariableBufferPayloadSize(match with mVariableBufferPayloadSize in VariableSmmRuntimeDxe) to hold communicate buffer payload to avoid TOCTOU issue.
2. Add check to ensure CommBufferPayloadSize not exceed mVariableBufferPayloadSize or is enough to hold function structure in VariableSmm and FtwSmm.
3. Align FtwGetLastWrite() in FaultTolerantWriteSmmDxe.c to FtwGetLastWrite() in FaultTolerantWrite.c.

Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14325 6f19259b-4bc3-4df7-8a09-765794883524