MIPS: Malta: fix alignment of the devicetree buffer

Starting with following patch MIPS Malta is not able to boot:
| commit 79edff12060fe7772af08607eff50c0e2486c5ba
| Author: Rob Herring <robh@kernel.org>
| scripts/dtc: Update to upstream version v1.6.0-51-g183df9e9c2b9

The reason is the alignment test added to the fdt_ro_probe_(). To fix
this issue, we need to make sure that fdt_buf is aligned.

Since the dtc patch was designed to uncover potential issue, I handle
initial MIPS Malta patch as initial bug.

Fixes: e81a8c7dabac ("MIPS: Malta: Setup RAM regions via DT")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>