[media] vivid: use ARRAY_SIZE to calculate max control value

The max value of various menu controls is hardcoded, and it is easy to forget
to update it after adding a new menu item.

So use ARRAY_SIZE instead to calculate this value.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>