e1000e: add support for IEEE-1588 PTP

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: Bruce Allan <bruce.w.allan@intel.com>
Reviewed-by: Jacob Keller <Jacob.e.keller@intel.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/Kconfig b/drivers/net/ethernet/intel/Kconfig
index 21353f0..3d5f6d4 100644
--- a/drivers/net/ethernet/intel/Kconfig
+++ b/drivers/net/ethernet/intel/Kconfig
@@ -74,6 +74,7 @@
 	tristate "Intel(R) PRO/1000 PCI-Express Gigabit Ethernet support"
 	depends on PCI && (!SPARC32 || BROKEN)
 	select CRC32
+	select PTP_1588_CLOCK
 	---help---
 	  This driver supports the PCI-Express Intel(R) PRO/1000 gigabit
 	  ethernet family of adapters. For PCI or PCI-X e1000 adapters,