V4L/DVB: ov7670: Restore SMBUS I/O for the XO 1.0

The Cafe controller doesn't do non-SMBUS I/O, so we have to use it there.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>