arm64: dts: qcom: msm8916: Use power domains for MSS/WCNSS remoteprocs

So far we have been making proxy votes for the remote processors
through the regulator interface. Now that we have rpmpd it's better
to vote for performance states through the power domain interface.

This also allows us to move these supplies back to msm8916.dtsi
because the device tree binding for RPMPD is independent of the
underlying regulator/PMIC.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20200916104135.25085-10-stephan@gerhold.net
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>