LU-4221 osd: 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:
- add case LCFG_PARAM to osd_process_config() to process parameters
  with prefix both PARAM_OSD and PARAM_OST.
- 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.
- get rid of lprocfs_osd_init_vars() and use struct lprocfs_vars
  lprocfs_osd_{obd,module}_vars[] instead.
- improve the error messages in class_process_proc_param() and
  class_process_proc_seq_param() a little.
- add conf-sanity.sh test_28a to verify the patch and skip this test
  for ZFS OSTs since ZFS has no such kind of parameters.

Signed-off-by: Emoly Liu <emoly.liu@intel.com>
Change-Id: I8f64dcc29017c3ed9da010ff0a3e40c02327f05c
Reviewed-on: http://review.whamcloud.com/8238
Tested-by: Jenkins
Tested-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>