ixgbe: link change interrupt was not causing link event

Upon review a buglet was found where link change was not causing
an immediate link change event as it should.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>