igb: Update PTP Rx filters

Update the filters to be more consistent with what the driver wants to do.
For example, for devices that timestamp all packets, report that the filter
is set for timestamping all packets.

Signed-off-by: Matthew Vick <matthew.vick@intel.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>