drm/xe/oa: Signal output fences

drm/xe/oa: Signal output fences

Introduce 'struct xe_oa_fence' which includes the dma_fence used to signal
output fences in the xe_sync array. The fences are signaled
asynchronously. When there are no output fences to signal, the OA
configuration wait is synchronously re-introduced into the ioctl.

v2: Don't wait in the work, use callback + delayed work (Matt B)
    Use a single, not a per-fence spinlock (Matt Brost)
v3: Move ofence alloc before job submission (Matt)
    Assert, don't fail, from dma_fence_add_callback (Matt)
    Additional dma_fence_get for dma_fence_wait (Matt)
    Change dma_fence_wait to non-interruptible (Matt)
v4: Introduce last_fence to prevent uaf if stream is closed with
    pending OA config jobs
v5: Remove oa_fence_lock, move spinlock back into xe_oa_fence to
    prevent uaf

Suggested-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241022200352.1192560-5-ashutosh.dixit@intel.com