media: imx: Parse information from firmware without using callbacks

Instead of using the convenience functions
v4l2_async_notifier_parse_fwnode_endpoints*() or
v4l2_async_register_fwnode_subdev(), parse the input endpoints
and set up the async sub-devices without using callbacks. The drivers
know which ports it must parse and how to handle unconnected remotes,
so it makes the code simpler to transfer control of endpoint parsing
to the driver.

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