sfc: Do not use MAC address as clock name

We'll be sharing clocks between multiple functions with their own MAC
addresses.  The name field is now documented as 'A short "friendly
name" to identify the clock ...' and '... not meant to be a unique
id.'  So use the name 'sfc'.
Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>

drivers/net/ethernet/sfc/ptp.c

@@ -965,9 +965,8 @@ int efx_ptp_probe(struct efx_nic *efx, struct efx_channel *channel)
 	ptp->evt_overflow = false;
 
 	ptp->phc_clock_info.owner = THIS_MODULE;
-	snprintf(ptp->phc_clock_info.name,
-		 sizeof(ptp->phc_clock_info.name),
-		 "%pm", efx->net_dev->perm_addr);
+	strlcpy(ptp->phc_clock_info.name, "sfc",
+		sizeof(ptp->phc_clock_info.name));
 	ptp->phc_clock_info.max_adj = MAX_PPB;
 	ptp->phc_clock_info.n_alarm = 0;
 	ptp->phc_clock_info.n_ext_ts = 0;