Refactor BlGetConfigValue to return EFI_STATUS and output value via parameter

sdk/xtdk/bltypes.h

@@ -54,7 +54,7 @@ typedef EFI_STATUS (*PBL_CLOSE_XT_PROTOCOL)(IN PEFI_HANDLE Handle, IN PEFI_GUID
 typedef BOOLEAN (*PBL_CONFIG_GET_BOOLEAN_VALUE)(IN CONST PWCHAR ConfigName);
 typedef EFI_STATUS (*PBL_CONFIG_GET_BOOT_OPTION_VALUE)(IN PLIST_ENTRY Options, IN CONST PWCHAR OptionName, OUT PWCHAR *OptionValue);
 typedef VOID (*PBL_CONFIG_GET_EDITABLE_OPTIONS)(OUT CONST PWCHAR **OptionsArray, OUT PSIZE_T OptionsCount);
-typedef PWCHAR (*PBL_CONFIG_GET_VALUE)(IN CONST PWCHAR ConfigName);
+typedef EFI_STATUS (*PBL_CONFIG_GET_VALUE)(IN CONST PWCHAR ConfigName, OUT PWCHAR *ConfigValue);
 typedef EFI_STATUS (*PBL_CONFIG_SET_BOOT_OPTION_VALUE)(IN PLIST_ENTRY Options, IN CONST PWCHAR OptionName, IN CONST PWCHAR OptionValue);
 typedef VOID (*PBL_CONSOLE_CLEAR_SCREEN)();
 typedef VOID (*PBL_CONSOLE_DISABLE_CURSOR)();