platform/surface: aggregator_registry: Rename device registration function

Rename the device registration function to better align names with the
newly introduced device removal function.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20211028002243.1586083-4-luzmaximilian@gmail.com


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