Multi-SMM drivers couldn't save their boot script successfully all at runtime in...

Multi-SMM drivers couldn't save their boot script successfully all at runtime in SMM, one module's boot script will overwrite another module's.
Allocate a SMM copy for private data structure, and use a new PCD PcdS3BootScriptTablePrivateSmmDataPtr to transfer and share data between multi-SMM drivers.

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@13984 6f19259b-4bc3-4df7-8a09-765794883524