Silicon/SynQuacer/Fip006Dxe: implement standalone MM variant

Implement a variant of the FIP006 NOR flash driver that can execute
in standalone MM context. This is the foundation for hosting the
EFI authenticated variable store in the secure world.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>