Revert "drm/radeon: hold reference to fences in radeon_sa_bo_new"

This reverts commit 73187980, which was
commit f6ff4f67 upstream.

This patch was triggering a Oops in stable kernel 3.10.99.  Christian
agrees that the patch is correct but "assumes that radeon_fence_unref()
can safely take NULL as the fence which is not the case for older
kernels."
Reported-by: Erik Andersen <andersen@codepoet.org>
Acked-by: Christian König <christian.koenig@amd.com>
Cc: Nicolai Hähnle <nicolai.haehnle@amd.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/gpu/drm/radeon/radeon_sa.c

@@ -349,13 +349,8 @@ int radeon_sa_bo_new(struct radeon_device *rdev,
 			/* see if we can skip over some allocations */
 		} while (radeon_sa_bo_next_hole(sa_manager, fences, tries));
 
-		for (i = 0; i < RADEON_NUM_RINGS; ++i)
-			radeon_fence_ref(fences[i]);
-
 		spin_unlock(&sa_manager->wq.lock);
 		r = radeon_fence_wait_any(rdev, fences, false);
-		for (i = 0; i < RADEON_NUM_RINGS; ++i)
-			radeon_fence_unref(&fences[i]);
 		spin_lock(&sa_manager->wq.lock);
 		/* if we have nothing to wait for block */
 		if (r == -ENOENT) {