Revert "drm/amd/display: Fix unused variable warning"

This reverts commit f01afd1e.

Cc: Wayne Lin <Wayne.Lin@amd.com>
Cc: Alexander Deucher <Alexander.Deucher@amd.com>
Cc: Harry Wentland <Harry.Wentland@amd.com>
Cc: Roman Li <Roman.Li@amd.com>
Cc: Bindu R <Bindu.R@amd.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>