drm/amdgpu: always signal all fences

A little fallout from "drm/amdgpu: sanitize fence numbers", we
sometimes need to signal all fences in the ring.

Signed-off-by: Christian König <[e-mail]>
Reviewed-by: Alex Deucher <[e-mail]>
Reviewed-by: Chunming Zhou <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c

···
 	if (seq != ring->fence_drv.sync_seq)
 		amdgpu_fence_schedule_fallback(ring);
 
+	if (unlikely(seq == last_seq))
+		return;
+
 	last_seq &= drv->num_fences_mask;
 	seq &= drv->num_fences_mask;
 
-	while (last_seq != seq) {
+	do {
 		struct fence *fence, **ptr;
 
 		++last_seq;
···
 			BUG();
 
 		fence_put(fence);
-	}
+	} while (last_seq != seq);
 }
 
 /**