drm/amd/display: Adding log for spread_spectrum_info

[Why & How]
Enable logging for spread_spectrum_percentage in spread_spectrum_info
to facilitate debugging for audio compliance issues

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Co-authored-by: Leo Chen <SanChuan.Chen@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Pavle Kotarac <Pavle.Kotarac@amd.com>
Signed-off-by: Leo Chen <SanChuan.Chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>