IB/hfi1: Add cache evict LRU list

The original code used a LRU list to evict nodes which were least
recently used.  For correctness the evict code was moved under the
handler->lock, now add back the LRU list.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>