drm/amdgpu: force pa_sc_tile_steering_override to 0 for navy_flounder

pa_sc_tile_steering_override is only programmable for
gfx10.0/10.1/10.2, and navy_flounder has the same gfx10.3 IP
with sienna_cichlid.

Signed-off-by: Jiansong Chen <Jiansong.Chen@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>