net: ethtool: don't ignore return from driver get_fecparam method

If ethtool_ops->get_fecparam returns an error, pass that error on to the
 user, rather than ignoring it.

Fixes: 1a5f3da20bd9 ("net: ethtool: add support for forward error correction modes")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/ethtool.c

@@ -2520,11 +2520,14 @@ static int set_phy_tunable(struct net_device *dev, void __user *useraddr)
 static int ethtool_get_fecparam(struct net_device *dev, void __user *useraddr)
 {
 	struct ethtool_fecparam fecparam = { ETHTOOL_GFECPARAM };
+	int rc;
 
 	if (!dev->ethtool_ops->get_fecparam)
 		return -EOPNOTSUPP;
 
-	dev->ethtool_ops->get_fecparam(dev, &fecparam);
+	rc = dev->ethtool_ops->get_fecparam(dev, &fecparam);
+	if (rc)
+		return rc;
 
 	if (copy_to_user(useraddr, &fecparam, sizeof(fecparam)))
 		return -EFAULT;