ethtool: Clean up definitions of rule location arrays in RX NFC

Correct the description of ethtool_rxnfc::rule_locs; it is an array
of currently used locations, not all possible valid locations.

Add note that drivers must not use ethtool_rxnfc::rule_locs.

The rule_locs argument to ethtool_ops::get_rxnfc is either NULL or a
pointer to an array of u32, so change the parameter type accordingly.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/vmxnet3/vmxnet3_ethtool.c b/drivers/net/vmxnet3/vmxnet3_ethtool.c
index 27400ed..e662cbc 100644
--- a/drivers/net/vmxnet3/vmxnet3_ethtool.c
+++ b/drivers/net/vmxnet3/vmxnet3_ethtool.c
@@ -558,7 +558,7 @@
 
 static int
 vmxnet3_get_rxnfc(struct net_device *netdev, struct ethtool_rxnfc *info,
-		  void *rules)
+		  u32 *rules)
 {
 	struct vmxnet3_adapter *adapter = netdev_priv(netdev);
 	switch (info->cmd) {