drm/xe: Move queue init before LRC creation

drm/xe: Move queue init before LRC creation

A queue must be in the submission backend's tracking state before the
LRC is created to avoid a race condition where the LRC's GGTT addresses
are not properly fixed up during VF post-migration recovery.

Move the queue initialization—which adds the queue to the submission
backend's tracking state—before LRC creation.

Also wait on pending GGTT fixups before allocating LRCs to avoid racing
with fixups.

v2:
 - Wait on VF GGTT fixes before creating LRC (testing)
v5:
 - Adjust comment in code (Tomasz)
 - Reduce race window
v7:
 - Only wakeup waiters in recovery path (CI)
 - Wakeup waiters on abort
 - Use GT warn on (Michal)
 - Fix kernel doc for LRC ring size function (Tomasz)
v8:
 - Guard against migration not supported or no memirq (CI)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Tomasz Lis <tomasz.lis@intel.com>
Link: https://lore.kernel.org/r/20251008214532.3442967-28-matthew.brost@intel.com