mlxsw: reg: Update RALUE register with IPv6 support

Update the register so that IPv6 LPM entries could be programmed to the
device's table.

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>