arm: dts: qcom: use qcom,msm8974pro for pro devices

Use new qcom,msm8974pro compatible string instead of qcom,msm8974 to
clearly mark that the device is using the Pro version of the SoC.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221128131550.858724-2-dmitry.baryshkov@linaro.org