MdeModulePkg Variable: Handle ftw driver executes prior to variable driver

MdeModulePkg Variable:  Handle ftw driver executes prior to variable driver

Variable driver uses gEdkiiFaultTolerantWriteGuid hob and copies  data to NvStorageData if hob exists.
But if ftw driver executes prior to variable driver then spare block is erased.

So the patch is to enhance the code to do not check FTW last write data hob if FTW protocol has been installed.

Cc: Liming Gao <liming.gao@intel.com>
Reported-by: Baraneedharan Anbazhagan <anbazhagan@hp.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Baraneedharan Anbazhagan <anbazhagan@hp.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19577 6f19259b-4bc3-4df7-8a09-765794883524