Of_unflatten_dtb returns a ERR_PTR value so checking it against NULL is
incorrect. Fix it in all of the places where this was happening.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Device trees can be passed by primary boot loader or appended to
barebox binary. Unfortunately, before probing devices from such
a device tree, no fixup can be applied.

Add a call to of_fix_tree() right before probing devices to catch
some very early fixups.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

I assume I am the only person knowing that barebox is able to
merge devicetrees. This feature seems broken for a while now since
trying to merge devicetress results in:

unflatten: too many end nodes

Remove this feature to save the complexity.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Addionally to having a builtin DTB provide the possibility for
the board to provide a dtb via boarddata.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

- Add rules to generate dtb files in arch/arm/dts/
- add an initcall which unflattens and probes the internal devicetree
- Add skeleton devicetree

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>