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

The RAUHT register is used to configure and query the Unicast Host Table
in devices that implement the Algorithmic LPM. In other words, it is
used to configure neighbour entries in the device.

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