ARM: dts: qcom: mdm9615: split PMIC to separate dtsi files

ARM: dts: qcom: mdm9615: split PMIC to separate dtsi files

The PMIC is not a part of the SoC, so move PMIC to a separate file and
include it from the board files.

Suggested-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Acked-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20230928110309.1212221-19-dmitry.baryshkov@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>