media: i2c: ov08d10: Unlock on error in ov08d10_enum_frame_size()

This error path needs to drop the mutex to avoid a deadlock.

Fixes: 7be91e02

 ("media: i2c: Add ov08d10 camera sensor driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>