dt-bindings: display: rockchip,inno-hdmi: Document RK3128 compatible

The integration for this SoC is different from the currently existing: It
needs it's PHY's reference clock rate to calculate the DDC bus frequency
correctly. The controller is also part of a powerdomain, so this gets added
as an mandatory property for this variant.

Signed-off-by: Alex Bee <knaerzche@gmail.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231222174220.55249-2-knaerzche@gmail.com


Signed-off-by: Rob Herring <robh@kernel.org>