ionic: return -EFAULT if copy_to_user() fails

The copy_to_user() function returns the number of bytes that it wasn't
able to copy.  We want to return -EFAULT to the user.

Fixes: fee6efce ("ionic: add hw timestamp support files")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/pensando/ionic/ionic_phc.c

@@ -225,7 +225,9 @@ int ionic_lif_hwstamp_get(struct ionic_lif *lif, struct ifreq *ifr)
 	memcpy(&config, &lif->phc->ts_config, sizeof(config));
 	mutex_unlock(&lif->phc->config_lock);
 
-	return copy_to_user(ifr->ifr_data, &config, sizeof(config));
+	if (copy_to_user(ifr->ifr_data, &config, sizeof(config)))
+		return -EFAULT;
+	return 0;
 }
 
 static u64 ionic_hwstamp_read(struct ionic *ionic,