clk: qcom: clk-rpm: convert to parent_data API

Convert clk-rpm driver to parent_data API.
We keep the old pxo/cxo_board parent naming to keep compatibility with
old DT and we use the new pxo/cxo for new implementation where these
clock are defined in DTS.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220706225321.26215-4-ansuelsmth@gmail.com