ARM: dts: exynos: add unit address to DWC3 node wrapper in Exynos5250

ARM: dts: exynos: add unit address to DWC3 node wrapper in Exynos5250

Neither simple-bus bindings nor dtc W=1 accept device nodes in soc@ node
which do not have unit address.  Therefore usethe address space
of child device (actual DWC3 Controller) as the wrapper's address to
fix:

  exynos5250-smdk5250.dtb: soc: usb3: {'compatible': ['samsung,exynos5250-dwusb3'],
    ... } should not be valid under {'type': 'object'}

  exynos5250.dtsi:638.16-653.5: Warning (simple_bus_reg): /soc/usb3: missing or empty reg/ranges property

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20230127212713.267014-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>