ARM: dts: mvebu: move all peripherals inside soc

reorganize the .dts and .dtsi files so that all devices are under the
soc { } node (currently some devices such as the interrupt controller,
the L2 cache and a few others are outside).

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>