LU-4362 libcfs: wrong parameter to cfs_hash_keycpy

cfs_hash_rehash_key() passed wrong parameter to cfs_hash_keycpy,
hnode should be the second parameter not the third one.

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Change-Id: Ib5b61a2f2bbd85848429ae5eae3702cb98d548d8
Reviewed-on: http://review.whamcloud.com/8510
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Johann Lombardi <johann.lombardi@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>