mlxsw: Use Switch Flooding Table Register Version 2

The SFTR-V2 register is used for flooding packet replication.
It is a new version of SFTR in order to support 1024 bits of local_port.

Add SFTR-V2 register and use it instead of SFTR.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>