AT91 ramc and reset/poweroff related DT patches
This branch gathers a few devicetree patches needed for the reworks found in
the later patches to be sent. More precisely, it holds:
- The addition of ddrck for the sama5d3 and the sam9 SoCs
- The addition of the shutdown controller node in the sama5d3 DTSI
- The slight rework of the ramc bindings for the SoCs that have several RAM
controllers