mlxsw: spectrum: Extend to support Spectrum-3 ASIC

Extend existing driver for Spectrum and Spectrum-2 ASICs
to support Spectrum-3 ASIC as well.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>