media: dt-bindings: media: Add Cadence MIPI-CSI2 TX Device Tree bindings

The Cadence MIPI-CSI2 TX controller is a CSI2 bridge that supports up to 4
video streams and can output on up to 4 CSI-2 lanes, depending on the
hardware implementation.

It can operate with an external D-PHY, an internal one or no D-PHY at all
in some configurations.

Acked-by: Benoit Parrot <bparrot@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>