V4L/DVB (11713): gspca - ov534: Don't discard the images when no UVC EOF

A new image may start without any UVC EOF in the last packet of the
previous image.

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>