arm64: dts: exynos: add unit address to DWC3 node wrapper in Exynos7

arm64: dts: exynos: add unit address to DWC3 node wrapper in Exynos7

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:

  exynos7-espresso.dtb: soc@0: usb: {'compatible': ['samsung,exynos7-dwusb3'], ...
    should not be valid under {'type': 'object'}

Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Link: https://lore.kernel.org/r/20230127212713.267014-4-krzysztof.kozlowski@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>