staging/lustre/lmv: support DNE with HSM.

Send HSM requests to the appropriate MDT. Split lists of fids of HSM
actions into one list per MDT.
Move kuc registration/unregistration from MDC to LMV as this is not
MDT related.

Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3365
Lustre-change: http://review.whamcloud.com/6714


Signed-off-by: Thomas Leibovici <thomas.leibovici@cea.fr>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: jacques-Charles Lafoucriere <jacques-charles.lafoucriere@cea.fr>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>