media: imx7-mipi-csis: Remove unneeded 'ret' initialization

There is no need for initializing the 'ret' variable as it will
be assigned at:

	ret = mipi_csis_parse_dt(pdev, state);

Remove the unneeded initialization.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>