dts: Cleanup warnings associated with cpu node

When we fixed the missing reg property in the cpu node, we forgot to
add #address-cells & #size-cells for the node.

This fix the following warnings we get:
	Warning (reg_format): "reg" property in /cpus/cpu@0 has invalid
	length (4 bytes) (#address-cells == 2, #size-cells == 1)

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>