dt-bindings: usb: samsung,exynos-dwc3: allow unit address in DTS

dt-bindings: usb: samsung,exynos-dwc3: allow unit address in DTS

The Samsung Exynos SoC USB 3.0 DWC3 Controller is a simple wrapper of
actual DWC3 Controller device node.  It handles necessary Samsung
Exynos-specific resources (regulators, clocks), but does not have its
own MMIO address space.

However neither simple-bus bindings nor dtc W=1 accept device nodes in
soc@ node which do not have unit address.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230127211748.260718-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>