Check if VCN instances are harvested when controlling VCN power gating and setting up VCN clocks. Fixes: 1b592d00b4ac83 ("drm/amdgpu/vcn: remove manual instance setting") Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1743 Reviewed-and-tested-by: Guchun Chen <guchun.chen@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>