LU-6142 osc: remove oti_descr oti_handle oti_plist

LU-6142 osc: remove oti_descr oti_handle oti_plist

These three fields in 'struct osc_thread_info' are
unused, so remove them.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.com>
Change-Id: I8642ebd692f44eca9d9ddad3b8184cabb27d27b3
Reviewed-on: https://review.whamcloud.com/35889
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.super@gmail.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>