[media] ov2659: Don't depend on subdev API

The subdev API is optional. No driver should depend on it.

Avoid compilation breakages if subdev API is not selected:

drivers/media/i2c/ov2659.c: In function ‘ov2659_get_fmt’:
drivers/media/i2c/ov2659.c:1054:3: error: implicit declaration of function ‘v4l2_subdev_get_try_format’ [-Werror=implicit-function-declaration]
   mf = v4l2_subdev_get_try_format(sd, cfg, 0);
   ^
drivers/media/i2c/ov2659.c:1054:6: warning: assignment makes pointer from integer without a cast
   mf = v4l2_subdev_get_try_format(sd, cfg, 0);
      ^
drivers/media/i2c/ov2659.c: In function ‘ov2659_set_fmt’:
drivers/media/i2c/ov2659.c:1129:6: warning: assignment makes pointer from integer without a cast
   mf = v4l2_subdev_get_try_format(sd, cfg, fmt->pad);
      ^
drivers/media/i2c/ov2659.c: In function ‘ov2659_open’:
drivers/media/i2c/ov2659.c:1264:38: error: ‘struct v4l2_subdev_fh’ has no member named ‘pad’
     v4l2_subdev_get_try_format(sd, fh->pad, 0);
                                      ^

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Tested-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>