SecurityPkg EsalVariableDxeSal: Use input Global to make code more clear

SecurityPkg EsalVariableDxeSal: Use input Global to make code more clear

SecurityPkg\VariableAuthenticated\EsalVariableDxeSal\Variable.c
AutoUpdateLangVariable()
Global->PlatformLangCodes[VirtualMode] = AllocateRuntimeCopyPool
  (DataSize, Data);
ASSERT (mVariableModuleGlobal->PlatformLangCodes[VirtualMode] != NULL);

The patch is to use Global instead of mVariableModuleGlobal in the
ASSERT (XXX) to make code more clear although mVariableModuleGlobal is
equal to Global actually.

Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Amy Chan <amy.chan@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>
Reviewed-by: Amy Chan <amy.chan@intel.com>
Reviewed-by: Giri P Mudusuru <giri.p.mudusuru@intel.com>