arm64: dts: qcom: add pm8450 support

Add PM8450 PMIC device tree include file. It is going to be used by
SM8450-based devices.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220226205035.1826360-8-dmitry.baryshkov@linaro.org