1. Don't assume that flush the HOB variable to flash must be successful.
2. When no DELETED variable found, no variable space could be reclaimed, so just give some debug info and return EFI_SUCCESS.

Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14029 6f19259b-4bc3-4df7-8a09-765794883524