media: imx: Create missing links from CSI-2 receiver

The entities external to the i.MX6 IPU and i.MX7 now create the links
to their fwnode-endpoint connected entities in their notifier bound
callbacks. Which means imx_media_create_of_links() and
imx_media_create_csi_of_links() are no longer needed and are removed.

However there is still one case in which imx-media needs to create
fwnode-endpoint based links at probe completion. The v4l2-async framework
does not allow multiple subdevice notifiers to contain a duplicate
subdevice in their asd_list. Only the first subdev notifier that discovers
and adds that one subdevice to its asd_list will receive a bound callback
for it. Other subdevices that also have firmware endpoint connections to
this duplicate subdevice will not have it in their asd_list, and thus will
never receive a bound callback for it. In the case of imx-media, the one
duplicate subdevice in question is the i.MX6 MIPI CSI-2 receiver.

Until there is a solution to that problem, rewrite imx_media_create_links()
to add the missing links from the CSI-2 receiver to the CSIs and CSI muxes.
The function is renamed imx_media_create_csi2_links().

Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>