Without the 'dirty' flag properties are not written back to the
devicetree when synced. This means that new properties copied over to a
node are not always written out.
Fix this and add a test.
Signed-off-by: Simon Glass <sjg@chromium.org>
This permits implementation of a simple templating system, where a node
can be reused as a base for others.
For now this adds new subnodes after any existing ones.
Signed-off-by: Simon Glass <sjg@chromium.org>