drm/amdgpu:Always save uvd vcpu_bo in VM Mode

When UVD is in VM mode, there is not uvd handle exchanged,
uvd.handles are always 0. So vcpu_bo always need save,
Otherwise amdgpu driver will fail during suspend/resume.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105021


Signed-off-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org