media: i2c: imx290: Use device lock for the control handler

The link frequency and pixel rate controls are set without holding the
control handler lock, resulting in kernel warnings. As the value of
those controls depend on the format, the simplest fix is to use the
device lock for the control handler.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>