arm64: dts: qcom: sm8250-xiaomi-elish: fix USB maximum speed property

Fix typo in USB DWC3 node maximum speed property.

Fixes: a41b6175 ("arm64: dts: qcom: sm8250: Add device tree for Xiaomi Mi Pad 5 Pro")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230304130315.51595-1-krzysztof.kozlowski@linaro.org