net: fix ethtool->set_flags not intended -EINVAL return value

After commit d5dbda2380 "ethtool: Add
support for vlan accleration.", drivers that have NETIF_F_HW_VLAN_TX,
and/or NETIF_F_HW_VLAN_RX feature, but do not allow enable/disable vlan
acceleration via ethtool set_flags, always return -EINVAL from that
function. Fix by returning -EINVAL only if requested features do not
match current settings and can not be changed by driver.

Change any driver that define ethtool->set_flags to use
ethtool_invalid_flags() to avoid similar problems in the future
(also on drivers that do not have the problem).

Tested with modified (to reproduce this bug) myri10ge driver.

Cc: stable@kernel.org # 2.6.37+
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vmxnet3/vmxnet3_ethtool.c

@@ -304,8 +304,8 @@ vmxnet3_set_flags(struct net_device *netdev, u32 data)
 	u8 lro_present = (netdev->features & NETIF_F_LRO) == 0 ? 0 : 1;
 	unsigned long flags;
 
-	if (data & ~ETH_FLAG_LRO)
-		return -EOPNOTSUPP;
+	if (ethtool_invalid_flags(netdev, data, ETH_FLAG_LRO))
+		return -EINVAL;
 
 	if (lro_requested ^ lro_present) {
 		/* toggle the LRO feature*/