LU-6142 lustre: Make dev/body/type operations const

LU-6142 lustre: Make dev/body/type operations const

Many of
  struct md_device_operations
  struct dt_body_operations
  struct dt_object_operations
  struct dt_device_operations
  struct dt_index_operations
  struct lu_object_operations
  struct lu_device_operations
  struct lu_device_type_operations
are already const.  This patch makes the remainder 'const',
and changes a few to 'static'.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Ife82c870a27a9e68e57208d49f51983a552e86ec
Reviewed-on: https://review.whamcloud.com/39398
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>