ARM: dts: rcar-gen2: Add missing mmio-sram bus properties

"#address-cells", "#size-cells", and "ranges" are required properties
for devices nodes compatible with "mmio-sram", leading to warnings when
running "make dtbs_check":

    $ make dtbs_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/sram/sram.yaml
    arch/arm/boot/dts/r8a7791-koelsch.dt.yaml: sram@e63a0000: '#address-cells' is a required property
    arch/arm/boot/dts/r8a7791-koelsch.dt.yaml: sram@e63a0000: '#size-cells' is a required property
    arch/arm/boot/dts/r8a7791-koelsch.dt.yaml: sram@e63a0000: 'ranges' is a required property
    ...

Fix this by adding the missing properties to the mmio-sram device nodes
in the DTS files for all affected R-Car Gen2 and RZ/G1 SoCs.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20191213162604.1890-1-geert+renesas@glider.be