drm/amd/display: add debug option to bypass ssinfo from bios.

[Why&How]
add debug option to bypass ssinfo from bios.

Reviewed-by: Chris Park <Chris.Park@amd.com>
Acked-by: Solomon Chiu <solomon.chiu@amd.com>
Signed-off-by: Charlene Liu <Charlene.Liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>