remoteproc: qcom_wcnss: Allow replacing regulators with power domains

remoteproc: qcom_wcnss: Allow replacing regulators with power domains

So far we have been doing all proxy votes by voting for raw voltages/load
through the regulator interface. But actually VDDCX and VDDMX represent
power domains that should be preferably managed using corner votes
through the power domain interface.

Looking closer the code was actually never doing the proxy votes
correctly: The vddcx regulator is specified as:

	{ "vddcx", .super_turbo = true },

which is supposed to say that we should vote for the maximum corner
of the VDDCX power domain. But actually "super_turbo" is unused so
all we did so far is to enable the power domain. We did not vote for
it to scale to the maximum performance state.

Using them through the power domain interface allows voting for the
maximum performance state. However, we still need to support using
them through the regulator interface for old device trees.

The way this is implemented here is that we check if attaching the
two power domain succeeds. If yes, we skip the first "num_pd_vregs"
regulators in the "vregs" list and only request the remaining ones.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20200916104135.25085-9-stephan@gerhold.net
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>