MIPS: dts: bcm63268: Add missing properties to the TWD node

We currently have a DTC warning with the current DTS due to the lack of
a suitable #address-cells and #size-cells property:

  DTC     arch/mips/boot/dts/brcm/bcm63268-comtrend-vr-3032u.dtb
arch/mips/boot/dts/brcm/bcm63268.dtsi:115.5-22: Warning (reg_format): /ubus/timer-mfd@10000080/timer@0:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)
arch/mips/boot/dts/brcm/bcm63268.dtsi:120.5-22: Warning (reg_format): /ubus/timer-mfd@10000080/watchdog@1c:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)
arch/mips/boot/dts/brcm/bcm63268.dtsi:111.4-35: Warning (ranges_format): /ubus/timer-mfd@10000080:ranges: "ranges" property has invalid length (12 bytes) (parent #address-cells == 1, child #address-cells == 2, #size-cells == 1)

Fixes: d3db4b96 ("mips: dts: bcm63268: add TWD block timer")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>