media: imx7: fix smatch error

Fixes this smatch error:

drivers/staging/media/imx/imx7-mipi-csis.c:716 mipi_csis_set_fmt() error: we previously assumed 'fmt' could be null (see line 709)

fmt is never NULL, so remove the 'fmt &&' condition.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>