soc: qcom: rpmpd: Add MSM8939 power-domains

Add the shared modemcx/cx/mx power-domains found on MSM8939.

Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Jun Nie <jun.nie@linaro.org>
Link: https://lore.kernel.org/r/20200930100145.9457-3-jun.nie@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>