ARM: dts: qcom-msm8974pro-*: Use the 8974pro name in DT filenames

Add the 'pro' part to the filenames of DTs of devices that are based on
this SoC to make in easier to differentiate between Snapdragon 800- and
801-based platforms.

Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220415115633.575010-16-konrad.dybcio@somainline.org