i40e: rename i40e_ptp_enable to i40e_ptp_feature_enable

Reduces possible confusion and ambiguity in purpose of the ancillary
feature control entry point function.

Change-ID: I21d773c1a86878f6d061505185b596c788d1b7cc
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --cc drivers/net/ethernet/intel/i40e/i40e_ptp.c
Simple merge