mlxsw: reg: Add Monitoring Port Analyzer Table register

The MPAT register is used to query and configure the Switch Port Analyzer
(SPAN) table. This register is used to configure a port as a mirror output
port, while after that a mirrored input port can be bound using MPAR
register.

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