Enhance InitializeLanguage() to set PcdUefiVariableDefaultPlatformLang to PlatformLan...

Enhance InitializeLanguage() to set PcdUefiVariableDefaultPlatformLang to PlatformLang variable if the value of PlatformLang variable has been set an unsupported value(not one of PlatformLangCodes variable), and assert when default (Platform)Lang PCD value is not set to one of (Platform)LangCodes PCD value.

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@14307 6f19259b-4bc3-4df7-8a09-765794883524