CVE-2025-40360

In the Linux kernel, the following vulnerability has been resolved:

drm/sysfb: Do not dereference NULL pointer in plane reset

The plane state in __drm_gem_reset_shadow_plane() can be NULL. Do not
deref that pointer, but forward NULL to the other plane-reset helpers.
Clears plane->state to NULL.

v2:
- fix typo in commit description (Javier)