SecurityPkg: Use IsZeroGuid API for zero GUID checking

SecurityPkg: Use IsZeroGuid API for zero GUID checking

Instead of comparing a GUID with gZeroGuid via the CompareGuid API, the
commit uses the IsZeroGuid API to check if the given GUID is a zero GUID.

Cc: Chao Zhang <chao.b.zhang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>