arm: dts: rockchip: rk3288: move to 64 bit reg size

To make automatic Rockchip DT syncing possible from Linux to U-boot prepare
rk3288.dtsi by moving to 64 bit reg size.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>