drivers: video: Add support for composite controls

For controls that are dependent from others, we need to "cluster" them.
Whenever one or more controls of the same cluster are set or gotten,
only the callback of the 1st control of the cluster, i.e. the master
control, is called. The master control is the one that represents the
whole cluster.

A common type of control cluster is "auto"-cluster, e.g. auto_gain/gain,
auto_exposure/exposure, auto_white_balance/red_balance/blue_balance,
etc. If the cluster is in automatic mode, then the manual controls are
marked inactive and volatile which are read via get_volatile_ctrl().
If the cluster is put in manual mode, then the manual controls should
become active again and the volatile flag is cleared.

Re-implement the ov5640's autogain/analogue_gain controls with the new
auto cluster mechanism so that it work correctly and fully.

Signed-off-by: Phi Bang Nguyen <phibang.nguyen@nxp.com>