Draft: [v2025dev2] drivers: media: max-gmsl2-ser: Fix probing

Probing is failing for max_gmsl2_ser:

max_gmsl2_ser 1-0040: sub-device fwnode is an endpoint!
max_gmsl2_ser 1-0040: v4l2_async_register_subdev error

This is a result of additional checks and changes to async sub-device fwnode matching introduced in:

1029939b3782 media: v4l: async: Simplify async sub-device fwnode matching

Remove setting of sd.fwnode inline with update of similar drivers in this commit.

Signed-off-by: Martyn Welch martyn.welch@collabora.com