LU-8130 ldlm: simplify ldlm_ns_hash_defs[]

LU-8130 ldlm: simplify ldlm_ns_hash_defs[]

As the ldlm_ns_types are dense, we can use the type as
the index to the array, rather than searching through
the array for a match.
We can also discard nsd_hops as all hash tables now
use the same hops.
This makes the table smaller and the code simpler.

Change-Id: I2aebb9d533d676bed51a7422801545be4fbb7e1e
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-on: https://review.whamcloud.com/36220
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>