net: ethtool: Use the PHY time stamping interface.

The ethtool layer tests fields of the phy_device in order to determine
whether to invoke the PHY's tsinfo ethtool callback.  This patch
replaces the open coded logic with an invocation of the proper
methods.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ethtool/ioctl.c

@@ -2096,8 +2096,8 @@ static int ethtool_get_ts_info(struct net_device *dev, void __user *useraddr)
 	memset(&info, 0, sizeof(info));
 	info.cmd = ETHTOOL_GET_TS_INFO;
 
-	if (phydev && phydev->drv && phydev->drv->ts_info) {
-		err = phydev->drv->ts_info(phydev, &info);
+	if (phy_has_tsinfo(phydev)) {
+		err = phy_ts_info(phydev, &info);
 	} else if (ops->get_ts_info) {
 		err = ops->get_ts_info(dev, &info);
 	} else {