drm/amd/display: cleanup idents after a revert

[WHY]
The change has caused high idle memory clock speed and power
consumption at some resolutions and frame rates for Navi10

[HOW]
Reverted change "drm/amd/display: Fixed Intermittent blue
screen on OLED panel"
Reviewed-by: Aric Cyr  <aric.cyr@amd.com>
Acked-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Angus Wang <angus.wang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>