drm/amd/display: Fix MPO visual confirm

1. Need to blend non-active area to show visual confirm borders
2. Set number of Visual Confirm lines based on pipe instance
3. Set Different colors representing surface format of bottom most plan

Signed-off-by: Anthony Koo <anthony.koo@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>