Silicon/SynQuacer/Fip006Dxe: factor out DXE specific pieces

In preparation of creating a SMM version of the FIP006 NOR flash
driver, refactor the existing pieces into a core driver, the FVB
methods and the DXE instantiation code.

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