arm64: dts: qcom: ipq6018: Use lowercase hex

Use lowercase hex, as that's the preferred and overwhermingly present
style.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221212111037.98160-2-konrad.dybcio@linaro.org