Platform\Intel\MinPlatformPkg: Add Variable Policy library

Makes the changes because of the new added library instances: VariablePolicyLib
and VariablePolicyHelperLib

Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>
Reviewed-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Reviewed-by: Eric Dong <eric.dong@intel.com>