drm/amdgpu: fix dma_fence_wait without reference

			       struct drm_sched_entity *entity)

{

	struct amdgpu_ctx_entity *centity = to_amdgpu_ctx_entity(entity);

	unsigned idx = centity->sequence & (amdgpu_sched_jobs - 1);

	struct dma_fence *other = centity->fences[idx];

	struct dma_fence *other;

	unsigned idx;

	long r;

	spin_lock(&ctx->ring_lock);

	idx = centity->sequence & (amdgpu_sched_jobs - 1);

	other = dma_fence_get(centity->fences[idx]);

	spin_unlock(&ctx->ring_lock);

	if (!other)

		return 0;

	if (other) {

		signed long r;

	r = dma_fence_wait(other, true);

		if (r < 0) {

			if (r != -ERESTARTSYS)

	if (r < 0 && r != -ERESTARTSYS)

		DRM_ERROR("Error (%ld) waiting for fence!\n", r);

	dma_fence_put(other);

	return r;

}

	}

	return 0;

}

void amdgpu_ctx_mgr_init(struct amdgpu_ctx_mgr *mgr)

{