drm/radeon: return -ENOENT in fence_wait_next v2

We should signal the caller that we haven't waited at all.

v2: only change fence_wait_next not fence_wait_last.

Signed-off-by: Christian König <deathsimple@vodafone.de>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_fence.c

@@ -286,7 +286,7 @@ int radeon_fence_wait_next(struct radeon_device *rdev, int ring)
 	}
 	if (list_empty(&rdev->fence_drv[ring].emitted)) {
 		write_unlock_irqrestore(&rdev->fence_lock, irq_flags);
-		return 0;
+		return -ENOENT;
 	}
 	fence = list_entry(rdev->fence_drv[ring].emitted.next,
 			   struct radeon_fence, list);