drm/amd/dc: Trigger set power state task when display configuration changes

Revert "drm/amd/display: Remove call to amdgpu_pm_compute_clocks"

This reverts commit dcd473770e86517543691bdb227103d6c781cd0a.

when display configuration changes, dc need to update the changes
to powerplay, also need to trigger a power state task.
amdgpu_pm_compute_clocks is the interface to set power state task
either dpm enabled or powerplay enabled

Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>