drm/amd/display: safeguard compressor api

Only call compressor api if it's available.

Signed-off-by: Roman Li <Roman.Li@amd.com>
Reviewed-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>