drm/amd/display: Disable ABM when eDP is disabled

- Add immediate ABM disable when eDP is disabled
- Fix purple screen when ABM is mistakenly enabled
on non eDP display

Signed-off-by: Amy Zhang <Amy.Zhang@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>