qeth: omit outbound queue 3 for unicast packets in Priority Queuing on HiperSockets

On HiperSockets only outbound queues 0 to 2 are available for unicast
packets. Current Priority Queuing implementation in the qeth driver puts
outgoing packets in outbound queues 0 to 3.

This puts outgoing unicast packets into outbound queue 2 instead of
outbound queue 3 when using Priority Queuing on a HiperSocket.
Additionally, the default outbound queue cannot be set to outbound queue 3
on HiperSockets.

Signed-off-by: Hans Wippel <hwippel@linux.vnet.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>