staging: lustre: obd: add case LCFG_PARAM to osd_process_config

Some proc parameters were moved from ofd to osd module and only
their symlinks were kept in ofd for interoperability/compatibility.
To process this kind of config params passed by ofd, this patch is
to do the following fixes:

 - since these parameters are not included by the static lprocfs var
   list, a pre-check is added for them to avoid "unknown param" error
   message confuses the uses. If they are matched in this check, they
   will be passed to the osd directly.
 - improve the error messages in class_process_proc_param() and
   class_process_proc_seq_param() a little.

Signed-off-by: Emoly Liu <emoly.liu@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4221
Reviewed-on: http://review.whamcloud.com/8238


Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>