staging: lustre: obdclass: remove structure holes to reduce memory

Fix the alignment of fields in commonly-used structures to reduce
memory usage on the client and server.  Structures fixed:

ptlrpc_reply_state: reduced by 8 bytes
obd_device:         reduced by 16 bytes
niobuf_local:       reduced by 8 bytes

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3281
Reviewed-on: http://review.whamcloud.com/16692


Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>