mlxsw: switchib: Use generic listener struct for events

Change the event handling in Switchib to be comptible with Spectrum and
Switchx2.
Use the generic listener struct for the events. Init and fini them by loop
(and not by calling each event by its name).

Signed-off-by: Nogah Frankel <nogahf@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>