drm/edid: Allow to add checksum quirks

There are devices out there that have a broken checksum but otherwise report correct edid. Allow to add quirks for those as well.

I'd like to test drive that a bit since it still strikes me as odd that didn't see that earlier. @angus.ainslie could you see if you can add for your hardware as well? That would be a more targeted solution than https://source.puri.sm/Librem5/linux-next/-/merge_requests/495 . If that works I can look into sending this upstream (after some code movement which I left out here to ease rebasing for @martin.kepplinger).

I'll revisit this when working on mainlining the DP driver latest.

Signed-off-by: Guido Günther guido.gunther@puri.sm