dt-bindings: media: Convert marvell,mmp2-ccic to json-schema

Convert the marvell,mmp2-ccic binding to DT schema format using
json-schema. While at that this drops the "func" and "phy" clocks.

The driver consumes clocks with those names, but it's not clear
what are they for and they are not used in DT systems. "phy" is
probably a clock for the sensor and it would belong in the sensor
node.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
[robh: add additionalProperties]
Signed-off-by: Rob Herring <robh@kernel.org>