mlxsw: reg: Add Policy-Engine ACL Group Table register

The PAGT register is used for configuration of the ACL Group Table.

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