soc: qcom: Move power-domain drivers to the genpd dir

To simplify with maintenance let's move the qcom power-domain drivers to
the new genpd directory. Going forward, patches are intended to be managed
through a separate git tree, according to MAINTAINERS.

Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Konrad Dybcio <konrad.dybcio@linaro.org>
Cc: Andy Gross <agross@kernel.org>
Cc: <linux-arm-msm@vger.kernel.org>
Acked-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>