V4L/DVB (8521): gspca: Webcams with Sonix bridge and sensor ov7630 are VGA.

This fixes a bug introduced in c503a6f8332a (thanks to Hans de Goede).

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