media: dt-bindings: ov2685: convert to dtschema

Convert the text-based dt-bindings to yaml.

Changes from original txt:
* Take wording for various properties from other yaml bindings, this
  removes e.g. volt amount from schema since it isn't really relevant
  and the datasheet is a better source.
* Don't make reset-gpios a required property since it can be tied to
  DOVDD instead.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
[Sakari Ailus: bump the maxItems for data-lanes to two]
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>