i40evf: don't fire traffic IRQs when the interface is down

i40evf: don't fire traffic IRQs when the interface is down

There is always a possibility that MSI-X interrupts can get lost. To
keep this problem from stalling the driver, we fire all of our MSI-X
vectors during the watchdog routine. However, we should not fire the
traffic vectors when the interface is closed. In this case, just fire
vector 0, which is used for admin queue events.

As a result, we do not enable the interrupt cause for vector 0. This
can cause the admin queue handler to be called reentrantly, which
causes a scary "critical section violation" message to be logged,
even though no real damage is done.

Change-ID: Ic43a5184708ab2cb9a23fca7dedd808a46717795
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Acked-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>