drm/i915 fixes for v5.11-rc4:

- Allow the sysadmin to override security mitigations
- Restore clear-residual mitigations for ivb/byt
- Limit VFE threads based on GT
- GVT: fix vfio edid and full display detection
- Fix DSI DSC power refcounting
- Fix LPT CPU mode backlight takeover
- Disable RPM wakeref assertions during driver shutdown
- Fix DSI sequence sleeps