media: ov2685: Select VIDEO_V4L2_SUBDEV_API

VIDEO_V4L2_SUBDEV_API is required for v4l2_subdev_get_pad_*() functions.
Select it.

Fixes: ("media: i2c: ov2685: Add .get_selection() support")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>