media: i2c: ov08x40: Make remove callback return void

In commit ed5c2f5f ("i2c: Make remove callback return void") drivers
were updated to remove the return value of the remove callback, and
return void.

The OV08x40 was added after this commit but was not compile tested at
the time due to a KConfig issue, and this warning was missed.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 38fc5136 ("media: i2c: Add ov08x40 image sensor driver")
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>