"firmware/sysfb: Set firmware-framebuffer parent device" breaks lightdm on Ubuntu 22.04 using amdgpu

[Marek Olšák <maraeo@xxxxxxxxx>]

Hi Thomas,

Commit 9eac534db0013aff9b9124985dab114600df9081 as per the title
breaks (crashes?) lightdm (login screen) such that all I get is the
terminal. It's also reproducible with tag v6.9 where the commit is
present.

Reverting the commit fixes lightdm. A workaround is to bypass lightdm
by triggering auto-login. This is a bug report.

(For AMD folks: It's also reproducible with amd-staging-drm-next.)

Marek