Merge branch 'rhash-cleanups'

NeilBrown says:

====================
A few rhashtables cleanups

2 patches fixes documentation
1 fixes a bit in rhashtable_walk_start()
1 improves rhashtable_walk stability.

All reviewed and Acked.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>