i40e: remove irqs only when they are set up

Use an extra state variable to keep track of when the IRQs are fully
set up.  This keeps us from trying to unhook IRQs that already were
left unhooked in a failed reset recovery, e.g. when firmware is broken.

Change-ID: I073eb081e4ef8aedcbdf1ee0717c0ed64fa172f2
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>