drm/amd/display: add improvements for text display and HDR DWM and MPO

[Why]
Tune settings for improved text display.
Handle differences between DWM and MPO in HDR path.

[How]
Update sharpener LBA table.
Use HDR multiplier to calculate scalar matrix coefficients
 for HDR RGB MPO path.
Update unit tests.

Reviewed-by: Jun Lei <jun.lei@amd.com>
Signed-off-by: Samson Tam <Samson.Tam@amd.com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>