dm: Fix error handling when unflattening the DT

The error handling code does not current detect an error right away.
Adjust it to return immediately.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Tested-on: Beaver, Jetson-TK1
1 file changed