dtoc: Add some debugging when copying nodes

Show the operations being performed, when debugging is enabled.

Convert a mistaken 'print' in test_copy_subnodes_from_phandles() while we
are here.

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

tools/dtoc/fdt.py

@@ -249,6 +249,7 @@ class Prop:
         """
         if self.dirty:
             node = self._node
+            tout.debug(f'sync {node.path}: {self.name}')
             fdt_obj = node._fdt._fdt_obj
             node_name = fdt_obj.get_name(node._offset)
             if node_name and node_name != node.name:
@@ -716,9 +717,13 @@ class Node:
         'phandle' property is not copied since this might result in two nodes
         with the same phandle, thus making phandle references ambiguous.
         """
+        tout.debug(f'copy to {self.path}: {src.path}')
         for name, src_prop in src.props.items():
+            done = False
             if name != 'phandle' and name not in self.props:
                 self.props[name] = Prop(self, None, name, src_prop.bytes)
+                done = True
+            tout.debug(f"  {name}{'' if done else '  - ignored'}")
 
     def copy_node(self, src):
         """Copy a node and all its subnodes into this node

tools/dtoc/test_fdt.py

@@ -32,6 +32,7 @@ from dtoc.fdt import Type, BytesToValue
 import libfdt
 from u_boot_pylib import test_util
 from u_boot_pylib import tools
+from u_boot_pylib import tout
 
 #pylint: disable=protected-access
 
@@ -414,7 +415,7 @@ class TestNode(unittest.TestCase):
 
         # Make sure that the phandle for 'over' is not copied
         over = dst.FindNode('over')
-        print('keys', over.props.keys())
+        tout.debug(f'keys: {over.props.keys()}')
         self.assertNotIn('phandle', over.props.keys())
 
         # Check the merged properties, first the base ones in '/dest'