media: cedrus: choose default pixelformat in try_fmt

If an unsupported pixelformat is passed to try_fmt, then pick
the first valid pixelformat instead. This is more standard V4L2
behavior.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>