LU-9038 obdclass: handle early requests vs CT registering

LU-9038 obdclass: handle early requests vs CT registering

This patch addresses cases where CDT may start to send requests
before CT has fully registered with all MDTs and thus when the KUC
pipe kernel side has still not been initialized in
lmv_hsm_ct_register().
This will avoid Oops'es due to kkuc_groups[KUC_GRP_HSM] being
uninitialized/zero'ed and we rely on CDT to later retry.
sanity-hsm/test_402b has been added to verify.

Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
Change-Id: Ibccf2627aebe8da52128da5d90d24751394bf61d
Reviewed-on: https://review.whamcloud.com/25050
Reviewed-by: Quentin Bouget <quentin.bouget@cea.fr>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Henri Doreau <henri.doreau@cea.fr>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>