clk: qcom: lcc-ipq806x: convert to parent data

Convert lcc-ipq806x driver to parent_data API.
Change parent_name for pll4 to pxo_board to prepare the future to
eventually drop the double pxo board clk.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220724182329.9891-3-ansuelsmth@gmail.com