drm/msm/dp: split dp_ctrl_clk_enable into four functuions

Split the dp_ctrl_clk_enable() beast into four functions, each of them
doing just a single item: enabling or disabling core or link clocks.
This allows us to cleanup the dss_module_power structure and makes
several dp_ctrl functions return void.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/576105/
Link: https://lore.kernel.org/r/20240126-dp-power-parser-cleanup-v3-8-098d5f581dd3@linaro.org