nvk: rework locking to avoid races on global object list.

The queue submission code adds all currently active memory objects to the bo submission to the kernel, however another thread can be in the process of removing objects from that list, and freeing the kernel resources.

longer term we don't care about this, but for now we should close the race to allow testing.

This reworks the locking so that object create/removal are locked against submits, this might be a larger hammer than needed but it seems stable here against the race when running Talos.