drm/amd/display: Correct comment style

Acked-by: NAnson Jacob <Anson.Jacob@amd.com>
Signed-off-by: NRoy Chan <roy.chan@amd.com>
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>