media: ov5648: Don't pack controls struct

Don't pack the driver specific struct containing control pointers. This
lead to potential alignment issues when working with the pointers.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: e43ccb0a ("media: i2c: Add support for the OV5648 image sensor")
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>