dt-bindings: usb: qcom,dwc3: add binding for SM8450

Add the compatible string for USB controller for Qualcomm SM8450 SoC.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20211216113849.659856-1-vkoul@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>