atl1c: dont use highprio tx queue

This driver attempts to use two TX rings but lacks proper support :

1) IRQ handler only takes care of TX completion on first TX ring
2) the stop/start logic uses the legacy functions (for non multiqueue
drivers)

This means all packets witk skb mark set to 1 are sent through high
queue but are never cleaned and queue eventualy fills and block the
device, triggering the infamous "NETDEV WATCHDOG" message.

Lets use a single TX ring to fix the problem, this driver is not a real
multiqueue one yet.

Minimal fix for stable kernels.

Reported-by: Thomas Meyer <thomas@m3y3r.de>
Tested-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jay Cliburn <jcliburn@gmail.com>
Cc: Chris Snook <chris.snook@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>