drm/amd/display: Support "Broadcast RGB" drm property

drm/amd/display: Support "Broadcast RGB" drm property

[WHY]
The source device outputs a full RGB signal, but TV may
be set to use limited RGB. The mismatch in color
range leads to a degradation in image quality.
Display driver should have the ability to switch
between the full and limited RGB to match TV's settings.

[HOW]
Add support of the linux DRM "Broadcast RGB" property, which
indicates the Quantization Range (Full vs Limited) used.
User space can set this property to be "Automatic", "Full"
or "Limited 16:235" to adjust the output color range.

Reviewed-by: Jerry Zuo <jerry.zuo@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Yan Li <yan.li@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>