drm/amdgpu/vcn: set no_user_fence for VCN v2.0 enc/dec rings

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>
(cherry picked from commit e2b5499fca55f1a32960a311bbb62e35891eaf73)