gspca: First camera mode is skipped

If a device supports a resolution in 2 different formats, mode[0] is
skipped on first iteration and a different format is selected.

Example: 320x240/YUYV isn't reachable for OV534/ov772x

Signed-off-by: Florin Tudorache <florin_tudorache@live.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>