Use the new get_mbus_config and set_mbus_config pad operations in place
of the video operations currently in use.

Compared to other drivers where the same conversion has been performed,
ov6650 proved to be a bit more tricky, as the existing g_mbus_config
implementation did not report the currently applied configuration but
the set of all possible configuration options.

Adapt the driver to support the semantic of the two newly introduced
operations:
- get_mbus_config reports the current media bus configuration
- set_mbus_config applies only changes explicitly requested and updates
  the provided cfg parameter to report what has actually been applied to
  the hardware.

Compile-tested only.
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>