dm: test: Correct ordering of DM setup

We must call dm_scan_other() after devices from the device tree have been
created, since that function behaves differently if there is no bootstd
device.

Adjust the logic to achieve this.

Also fix the bootflow_system() test which was relying on this broken
behaviour.

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