When there's a Tx timeout for a queue which belongs to a PFC enabled TC,
then it's not because the queue is hung but because PFC is in action.

In PFC, peer sends a pause frame for a specified period of time when its
buffer threshold is exceeded (due to congestion). Netdev on the other
hand checks if ACK is received within a specified time for a TX packet, if
not, it'll invoke the tx_timeout routine.
Signed-off-by: NAvinash JD <avinash.dayanand@intel.com>
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>