[media] uvcvideo: Set bandwidth to at least 1024 with the FIX_BANDWIDTH quirk

The bandwidth estimate computed with the FIX_BANDIWDTH quirk is too low
for many cameras. Don't use maximum packet sizes lower than 1024 bytes
to try and work around the problem. According to measurements done on
two different camera models, the value is high enough to get most
resolutions working while not preventing two simultaneous VGA streams at
15 fps.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>