drm/todos: add entry for drm_syncobj error handling

That would be rather nice to have and the kernel side is really trivial,
only the userspace side might be a bit more complex.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240826122541.85663-4-christian.koenig@amd.com