net/mlx4_en: fix mlx4 ethtool -N insertion

ethtool expects ETHTOOL_GRXCLSRLALL to set ethtool_rxnfc->data with the
total number of entries in the rx classifier table.  Surprisingly, mlx4
is missing this part (in principle ethtool could still move forward and
try the insert).

Tested: compiled and run command:
	phh13:~# ethtool -N eth1 flow-type udp4  queue 4
	Added rule with ID 255
Signed-off-by: Luigi Rizzo <lrizzo@google.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>

drivers/net/ethernet/mellanox/mlx4/en_ethtool.c

@@ -1745,6 +1745,7 @@ static int mlx4_en_get_rxnfc(struct net_device *dev, struct ethtool_rxnfc *cmd,
 		err = mlx4_en_get_flow(dev, cmd, cmd->fs.location);
 		break;
 	case ETHTOOL_GRXCLSRLALL:
+		cmd->data = MAX_NUM_OF_FS_RULES;
 		while ((!err || err == -ENOENT) && priority < cmd->rule_cnt) {
 			err = mlx4_en_get_flow(dev, cmd, i);
 			if (!err)