Document drm_sched_fini and add some warnings and a BUG_ON()

[Christian König]

Gentle ping.

Dave Philip noted in private chat that you had some comments? I don't 
see anything in my inbox.

Thanks,
Christian.

Am 27.09.24 um 16:27 schrieb Christian König:
> Sorry for sending incomplete patches earlier today, I've messed up my
> branch and had to re-create it.
>
> Let's try this again,
> Christian.
>
>