dt-bindings: usb: snps,dwc3: Fix "snps,hsphy_interface" type

The "snps,hsphy_interface" is string, not u8. Fix the type.

Fixes: 389d7765 ("dt-bindings: usb: Convert DWC USB3 bindings to DT schema")
Cc: stable <stable@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20230515172456.179049-1-marex@denx.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>