drm/msm/dp: inline dp_power_(de)init

In preparation to cleanup of the dp_power module, inline dp_power_init()
and dp_power_deinit() functions, which are now just turning the clocks
on and off.

Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
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/576113/
Link: https://lore.kernel.org/r/20240126-dp-power-parser-cleanup-v3-4-098d5f581dd3@linaro.org