MIPS: ath79: Add basic device tree support

Add the bare minimum to load a device tree.

Signed-off-by: Alban Bedel <albeu@free.fr>
Cc: linux-mips@linux-mips.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --cc arch/mips/Kconfig
Simple merge

diff --cc arch/mips/ath79/machtypes.h
Simple merge

diff --cc arch/mips/ath79/setup.c
Simple merge