This ports the following barebox commit:

| commit 119f92b
| Author: Sascha Hauer <s.hauer@pengutronix.de>
| Date:   Fri Jun 23 12:43:14 2017 +0200
|
|     state: backend: always pass backend type to Linux dtb
|
|     When the "backend-storage-type" property is unset in the barebox dtb
|     then barebox will use the default. Instead of leaving the property
|     unset in the Linux dtb, set it to the value we used as default. By
|     making the default explicit to Linux we force Linux to the same backend
|     type, even when the defaults may differ.
|
|     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>