mlxsw: reg: Add Router Algorithmic LPM Unicast Host Table Dump register

The RAUHTD register allows dumping entries from the Router Unicast Host
Table.

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