This ports the following barebox commit:

| commit b30047b
| Author: Sascha Hauer <s.hauer@pengutronix.de>
| Date:   Thu May 4 11:58:23 2017 +0200
|
|     state: warn when a state node will be overwritten
|
|     People do not seem to know that a state node in the kernel
|     device tree will be overwritten by barebox. Print a warning
|     when this happens so that people can get an idea why changes
|     in the kernel device tree state node do not have any effect.
|
|     Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Signed-off-by: Ulrich Ölmann <u.oelmann@pengutronix.de>
Signed-off-by: Roland Hieber <rhi@pengutronix.de>