greybus: svc: implement module inserted and removed operations

Implement the new module inserted and removed operations.

The SVC sends these after detecting a module insertion or removal, and
in the former case after having determined the module geometry (i.e.
position and size).

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>