drm/amd/display: disable idle optimizations

Disable idle optimizations until SMU can handle them to prevent DMUB
timeout and subsequent system freeze

Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Acked-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>