fdt: Allow more general use of livetree

At present livetree can only be used for the control FDT. It is useful
to be able to use the ofnode API for other FDTs, e.g. those used by
the upcoming configuration editor.

We already have most of the support present, and tests can be marked with
the UT_TESTF_OTHER_FDT flag to use another FDT as a special case. But
with this change, the functionality becomes more generally available.

Plumb in the require support.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/dm/ofnode.h

@@ -352,6 +352,16 @@ static inline oftree oftree_from_np(struct device_node *root)
 	return tree;
 }
 
+/**
+ * oftree_dispose() - Dispose of an oftree
+ *
+ * This can be used to dispose of a tree that has been created (other than
+ * the control FDT which must not be disposed)
+ *
+ * @tree: Tree to dispose
+ */
+void oftree_dispose(oftree tree);
+
 /**
  * ofnode_name_eq() - Check if the node name is equivalent to a given name
  *                    ignoring the unit address