CVE-2022-48893

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

drm/i915/gt: Cleanup partial engine discovery failures

If we abort driver initialisation in the middle of gt/engine discovery,
some engines will be fully setup and some not. Those incompletely setup
engines only have 'engine->release == NULL' and so will leak any of the
common objects allocated.

v2:
- Drop the destroy_pinned_context() helper for now. It's not really
worth it with just a single callsite at the moment. (Janusz)