mlxsw: reg: Add support for activity information from PEFA register

In Spectrum-2, the PEFA register is extend to report if the action set
was hit during processing of packets. Introduce this extension and
adjust the code around this accordingly.

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