ixgbe: fix crash when injecting AER after failed reset

In case where AER recovery fails the device is left in a down state.
Consecutive AER error injection can lead to a double IRQ free.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>