drm/amdgpu/vcn: set no_user_fence for VCN v2.0 enc/dec rings
VCN encoder and decoder rings do not support 64-bit user fence writes,
reject CS submissions with user fences.
Fixes: 1b61de45dfaf ("drm/amdgpu: add initial VCN2.0 support (v2)") Reviewed-by: Christian König <christian.koenig@amd.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Yinjie Yao <yinjie.yao@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>