Fix the TOCTOU issue of CommBufferSize itself for SMM communicate handler input.

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@14379 6f19259b-4bc3-4df7-8a09-765794883524
When finish using the browser storage for one formset, browser should clean the ConfigRequest string for this formset.

Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14380 6f19259b-4bc3-4df7-8a09-765794883524