soc: qcom: rpmpd: Add a Power domain driver to model corners

The Power domains for corners just pass the performance state set by the
consumers to the RPM (Remote Power manager) which then takes care
of setting the appropriate voltage on the corresponding rails to
meet the performance needs.

We add all power domain data needed on msm8996 here. This driver can easily
be extended by adding data for other qualcomm SoCs as well.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>