drm/imagination: only init job done fences once

Ensure job done fences are only initialised once.

This fixes a memory manager not clean warning from drm_mm_takedown
on module unload.

Cc: stable@vger.kernel.org
Fixes: eaf01ee ("drm/imagination: Implement job submission and scheduling")
Signed-off-by: Brendan King <brendan.king@imgtec.com>
Reviewed-by: Matt Coster <matt.coster@imgtec.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250226-init-done-fences-once-v2-1-c1b2f556b329@imgtec.com
Signed-off-by: Matt Coster <matt.coster@imgtec.com>

Author: brendan-king

drivers/gpu/drm/imagination/pvr_queue.c

@@ -313,8 +313,9 @@ pvr_queue_cccb_fence_init(struct dma_fence *fence, struct pvr_queue *queue)
 static void
 pvr_queue_job_fence_init(struct dma_fence *fence, struct pvr_queue *queue)
 {
-	pvr_queue_fence_init(fence, queue, &pvr_queue_job_fence_ops,
-			     &queue->job_fence_ctx);
+	if (!fence->ops)
+		pvr_queue_fence_init(fence, queue, &pvr_queue_job_fence_ops,
+				     &queue->job_fence_ctx);
 }
 
 /**