Add PTP IEEE-1588 support and make accesible via the PHC subsystem.

v2: make e1000e_ptp_clock_info a static const struct per Stephen Hemminger

Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: NBruce Allan <bruce.w.allan@intel.com>
Reviewed-by: NJacob Keller <Jacob.e.keller@intel.com>
Acked-by: NRichard Cochran <richardcochran@gmail.com>
Tested-by: NJeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>