drm/amdgpu: return -ENOENT from uvd 6.0 early init for harvesting

commit cb4b02d7cac56a69d8137d8d843507cca9182aed upstream.

Fixes init failures on polaris cards with harvested UVD.

Signed-off-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>