ARM: dts: uniphier: add #address-cells and #size-cells to SPI nodes

Documentation/devicetree/bindings/spi/spi-uniphier.txt requires
#address-cells and #size-cells, but they are missing in actual DT files.

Also, 'make ARCH=arm dtbs_check' is really noisy.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>