media: ti: cal: fix useless variable init

'ret' is initialized needlessly in cal_legacy_try_fmt_vid_cap(). We can
also move the variable to the for block, which is the only place where
it is used.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>