Revert "Return -1 from arc_shrinker_func()"
This reverts commit c11a12bc3b2e5ee9a6bd74e26f1a396b6025fbd4.
Out of memory events were fixed by reverting this patch.
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2110