V4L/DVB (11116): ov7670: cleanup and remove legacy code.

v4l2-i2c-drv-legacy.h and ov7670_command are no longer needed after the
cafe driver is converted to use v4l2_subdev.

Rather than using a large ov7670_control array, just call the handlers
via a simple switch and use v4l2_ctrl_query_fill() to handle queryctrl.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>