firewire: a header cleanup

fw_node() is not used (and not useful) outside fw-topology.c.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/fw-topology.c b/drivers/firewire/fw-topology.c
index 39e5cd1..45e6f9b 100644
--- a/drivers/firewire/fw-topology.c
+++ b/drivers/firewire/fw-topology.c
@@ -152,6 +152,10 @@
 	node->max_hops = max(max_child_hops, depths[0] + depths[1] + 2);
 }
 
+static inline struct fw_node *fw_node(struct list_head *l)
+{
+	return list_entry(l, struct fw_node, link);
+}
 
 /**
  * build_tree - Build the tree representation of the topology