media: pci: mgb4: Added Digiteq Automotive MGB4 driver

Digiteq Automotive MGB4 is a modular frame grabber PCIe card for automotive
video interfaces. As for now, two modules - FPD-Link and GMSL - are
available and supported by the driver. The card has two inputs and two
outputs (FPD-Link only).

In addition to the video interfaces it also provides a trigger signal
interface and a MTD interface for FPGA firmware upload.

Signed-off-by: Martin Tůma <martin.tuma@digiteqautomotive.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>