staging/lustre/osc: LBUG in osc_lru_reclaim

LASSERT touches cl_client_cache->ccc_lru without any protection.
So this patch the LASSERT moves to the section protected by
cl_client_cache->ccc_lru_lock

Signed-off-by: Hiroya Nozaki <nozaki.hiroya@jp.fujitsu.com>
Reviewed-on: http://review.whamcloud.com/14901
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6624


Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>