GSD-2022-1007749 drm: Fix potential null-ptr-deref in drm_vblank_destroy_worker()

drm: Fix potential null-ptr-deref in drmvblankdestroyworker This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v6.0.10 by commit...