e1000e: fix PTP on e1000_pch_lpt variants

I've got reports that the Intel I-218V NIC in Intel NUC5i5RYH systems used
as a PTP slave experiences random ~10 hour clock jumps, which are resolved
if the same workaround for the 82574 and 82583 is employed, so set the
appropriate flag2 in e1000_pch_lpt_info too.

Reported-by: Rupesh Patel <rupatel@redhat.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>