drm/xe/vf: Wakeup in GuC backend on VF post migration recovery

drm/xe/vf: Wakeup in GuC backend on VF post migration recovery

If VF post-migration recovery is in progress, the recovery flow will
rebuild all GuC submission state. In this case, exit all waiters to
ensure that submission queue scheduling can also be paused. Avoid taking
any adverse actions after aborting the wait.

As part of waking up the GuC backend, suspend_wait can now return
-EAGAIN indicating the waiter should be retried. If the caller is
running on work item, that work item need to be requeued to avoid a
deadlock for the work item blocking the VF migration recovery work item.

v3:
 - Don't block in preempt fence work queue as this can interfere with VF
   post-migration work queue scheduling leading to deadlock (Testing)
 - Use xe_gt_recovery_inprogress (Michal)
v5:
 - Use static function for vf_recovery (Michal)
 - Add helper to wake CT waiters (Michal)
 - Move some code to following patch (Michal)
 - Adjust commit message to explain suspend_wait returning -EAGAIN (Michal)
 - Add kernel doc to suspend_wait around returning -EAGAIN
v7:
 - Add comment on why a shared wait queue is need on VFs (Michal)
 - Guard again suspend_wait signaling early on resfix donw (Tomasz)
v8:
 - Fix kernel doc (CI)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://lore.kernel.org/r/20251008214532.3442967-18-matthew.brost@intel.com