LU-8066 obd_type: use typ_kobj.name as typ_name

LU-8066 obd_type: use typ_kobj.name as typ_name

As the kobject has a name (after kobject_add has been called),
we don't need to also store it in typ_name.
So use typ_kobj.name instead of typ_name.

This requires changing some "char *" to "const char *" as
typ.kobj.name is const.

Change-Id: Iaf0ef192e91ba1b4bd1c1b124dc1068de632d341
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-on: https://review.whamcloud.com/34717
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Petros Koutoupis <pkoutoupis@cray.com>