i40e: Re-enable interrupt on ICR0

The hardware can occasionally give an interrupt on the misc
queue for which there is no driver work to do.  In that case
the driver was not re-enabling interrupts even though they
were auto masked by hardware.  This left interrupts disabled
on this queue.

Re-enable the interrupt whenever leaving this function.

Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>