i40e: fix XPS mask when resetting

During resets (possibly caused by a Tx hang) the driver would
accidentally clear the XPS mask for all queues back to 0.

This caused higher CPU utilization and had some other performance impacts
for transmit tests.

Change-ID: I95f112432c9e643a153eaa31cd28cdcbfdd01831
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>