V4L/DVB (12077): gspca_ov519: Fix 320x240 with ov7660 sensor

As reported on the ov51x-jpeg list, and as I can confirm with my own cam
the ov7670 in 320x240 has a number of broken columns of pixels
at the left of the picture. This was not present in the old
driver as it always used 640x480 and did software
downscaling (took me a while to figure that one out).
The fix adds a sensor specific if in so far sensor
neutral code :( But this is the only way to fix this,
this cannot be fixed by only changing sensor registers.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>