Enable some more support for r-car devices

The audio graph 2 sound car is use by r-car ULCB devices

Signed-off-by: Sjoerd Simons <sjoerd@collabora.com>

This clock generator is part of the various r-car ULCB boards; primarily
for the display subsystem

Signed-off-by: Sjoerd Simons <sjoerd@collabora.com>

Enable the r-car iommu driver; needed for display out and some other
functionality

Signed-off-by: Sjoerd Simons <sjoerd@collabora.com>

Enable support for the r-car HDMI TX chip; Also drop some configuration
option that will default to the right value

Signed-off-by: Sjoerd Simons <sjoerd@collabora.com>