i40e: enable PTP

New feature: Enable PTP support in the i40e driver.

Change-ID: I6a8e799f582705191f9583afb1b9231a8db96cc8
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Matthew Vick <matthew.vick@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/Kconfig

@@ -243,6 +243,7 @@ config IXGBEVF
 
 config I40E
 	tristate "Intel(R) Ethernet Controller XL710 Family support"
+	select PTP_1588_CLOCK
 	depends on PCI
 	---help---
 	  This driver supports Intel(R) Ethernet Controller XL710 Family of