mlxsw: core: Create a generic function to register / unregister traps

We have 2 types of HW traps to handle, rx traps and events.
The registration workflow for both is very similar. So it only make
sense to create one function to handle both.

This patch creates a struct to hold the data for both cases. It also
creates a registration and an un-registration functions that get this
generic struct as input.

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>