drm/amd/display: default values for luminance range if they are 0

[why]
Currently if invalid luminescence range is reported in edid,
then the driver doesn't have default range to fallback to.

[How]
Add default range if, the range is 0.

Reviewed-by: Roman Li <Roman.Li@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Swapnil Patel <Swapnil.Patel@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>