e1000e: resolve -Wunused-parameter compile warnings

Remove the unused parameter when possible, otherwise use __always_unused
attribute.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/e1000e/ptp.c b/drivers/net/ethernet/intel/e1000e/ptp.c
index 6b8df65..b477fa5 100644
--- a/drivers/net/ethernet/intel/e1000e/ptp.c
+++ b/drivers/net/ethernet/intel/e1000e/ptp.c
@@ -165,8 +165,9 @@
  * Enable (or disable) ancillary features of the PHC subsystem.
  * Currently, no ancillary features are supported.
  **/
-static int e1000e_phc_enable(struct ptp_clock_info *ptp,
-			     struct ptp_clock_request *request, int on)
+static int e1000e_phc_enable(struct ptp_clock_info __always_unused *ptp,
+			     struct ptp_clock_request __always_unused *request,
+			     int __always_unused on)
 {
 	return -EOPNOTSUPP;
 }