media: imx: capture: Remove unneeded variable in __capture_legacy_try_fmt

The __capture_legacy_try_fmt() function doesn't need two
imx_media_pixfmt pointer variables. Remove one of them.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Reviewed-by: Steve Longerbeam <slongerbeam@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>