media: staging: rkisp1: remove serialization item in the TODO file

The item 'Fix serialization on subdev ops.' was solved,
so remove it from the TODO file.
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Acked-by: Helen Koike <helen.koike@collabora.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/staging/media/rkisp1/TODO

-* Fix serialization on subdev ops.
 * Don't use v4l2_async_notifier_parse_fwnode_endpoints_by_port().
 e.g. isp_parse_of_endpoints in drivers/media/platform/omap3isp/isp.c
 cio2_parse_firmware in drivers/media/pci/intel/ipu3/ipu3-cio2.c.