[media] adv7343: use control framework

Also fixed a memory leak in the probe function if an error occurred.
The gain control range was also fixed (a proper range from -64 to 64).

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>