ARM: dts: qcom-msm8974: Sort and clean up nodes

- Remove regulators from the SoC DTSI
- cpu_pmu{} -> pmu{}
- move modem/iris regulators out of here; only FP2 used them
- tcsr_mutex is moved out of /soc

Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
[bjorn: Rebased on top of Krzysztof's fixes]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220415115633.575010-18-konrad.dybcio@somainline.org