platform/surface: aggregator: Make client device removal more generic

Currently, there are similar functions defined in the Aggregator
Registry and the controller core.

Make client device removal more generic and export it. We can then use
this function later on to remove client devices from device hubs as well
as the controller and avoid re-defining similar things.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20211028002243.1586083-2-luzmaximilian@gmail.com


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>