mlxsw: reg: Add QoS Switch Traffic Class Table is Multicast-Aware Register

This register configures if the Switch Priority to Traffic Class mapping
is based on Multicast packet indication. If so, then multicast packets
will get a Traffic Class that is plus (cap_max_tclass_data/2) the value
configured by QTCT.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>