sfc: Add PTP counters to ethtool stats

These were implemented by Andrew Jackson and Laurence Evans but not
previously included in-tree.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
diff --git a/drivers/net/ethernet/sfc/nic.h b/drivers/net/ethernet/sfc/nic.h
index 170ac6e..a001fae 100644
--- a/drivers/net/ethernet/sfc/nic.h
+++ b/drivers/net/ethernet/sfc/nic.h
@@ -566,6 +566,8 @@
 			unsigned int new_mode);
 int efx_ptp_tx(struct efx_nic *efx, struct sk_buff *skb);
 void efx_ptp_event(struct efx_nic *efx, efx_qword_t *ev);
+size_t efx_ptp_describe_stats(struct efx_nic *efx, u8 *strings);
+size_t efx_ptp_update_stats(struct efx_nic *efx, u64 *stats);
 void efx_time_sync_event(struct efx_channel *channel, efx_qword_t *ev);
 void __efx_rx_skb_attach_timestamp(struct efx_channel *channel,
 				   struct sk_buff *skb);