net/mlx4_core: Fix memory leak while delete slave's resources

mlx4_delete_all_resources_for_slave in resource tracker should free all
memory allocated for a slave.
While releasing memory of fs_rule, it misses releasing memory of
fs_rule->mirr_mbox.

Fixes: 78efed27 ('net/mlx4_core: Support mirroring VF DMFS rules on both ports')
Signed-off-by: Moshe Shemesh <moshe@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -5088,6 +5088,7 @@ static void rem_slave_fs_rule(struct mlx4_dev *dev, int slave)
 						 &tracker->res_tree[RES_FS_RULE]);
 					list_del(&fs_rule->com.list);
 					spin_unlock_irq(mlx4_tlock(dev));
+					kfree(fs_rule->mirr_mbox);
 					kfree(fs_rule);
 					state = 0;
 					break;