i40e: Removing hung_queue variable to use txqueue function parameter

The scope of function .ndo_tx_timeout was changed to include the hang
queue when a TX timeout event occurs. See commit 0290bd29
("netdev: pass the stuck queue to the timeout handler") for more
details. Now, drivers don't need to identify which queue is stopped.
Drivers can simply use the queue index provided by dev_watchdog and
execute all actions needed to restore network traffic. This commit do
some cleanups into Intel i40e driver to remove a redundant loop to find
stopped queue.

Signed-off-by: Julio Faracco <jcfaracco@gmail.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>