drm/msm/hdmi: switch hdmi_pll_8960 to use parent_data

drm/msm/hdmi: switch hdmi_pll_8960 to use parent_data

Replace parent_names usage with parent_data. Note, that this makes the
PLL default to board's `pxo_board' clock rather than just `pxo' clock,
as we are on a way to deprecate the global cxo/pxo clocks.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/519210/
Link: https://lore.kernel.org/r/20230119132219.2479775-4-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>