drm/dp: Pull drm_dp_link_power_up/down from Tegra to common drm_dp_helper

drm/dp: Pull drm_dp_link_power_up/down from Tegra to common drm_dp_helper

The helper functions drm_dp_link_power_up/down were moved to Tegra
DRM in commit 9a42c7c647a9 ("drm/tegra: Move drm_dp_link helpers to Tegra DRM")".

Now since more and more users are duplicating the same code in their
own drivers, it's time to make them as DRM DP common helpers again.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Acked-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250318063452.4983-1-andyshrk@163.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>