LU-6409 nodemap: don't destroy nodemaps in cfs_hash_for_each

LU-6409 nodemap: don't destroy nodemaps in cfs_hash_for_each

nodemap_destroy might sleep, but cfs_hash_for_each iterators aren't
allowed to sleep. This patch changes nodemap_cleanup_all to avoid
destroying nodemaps in its cfs_hash_for_each iterator. Instead, the
iterator creats a list of nodemaps, and then all the nodemaps in the
list are destroyed.

Signed-off-by: Kit Westneat <kit.westneat@gmail.com>
Change-Id: I1d16f61ba7739af0494944f6515508b3f0d19ba1
Reviewed-on: http://review.whamcloud.com/14275
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Andrew Perepechko <andrew.perepechko@seagate.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>