[Intel-gfx] Some lost drm patches v2

[Damien Lespiau]

Updated series with:

- Reviews applied,
- Drop a patch that would conflict with Ville's latest changes,
- Drop Chris (Cummins)'s patch as he rebased it on top of drm-next and sent it
  back himself,
- Add a suggestion from Chris (Wilson) to not repeat the message in the poll
  handler. I did not do that for the irq helper as it might be useful to detect
  spurious interrupts.
 
-- 
Damien