Add an implementation of the StandaloneMmDriverEntryPoint library class. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Star Zeng <star.zeng@intel.com> Reviewed-by: Liming Gao <liming.gao@intel.com>