LU-6142 llog: remove olg_cat_processing field.

LU-6142 llog: remove olg_cat_processing field.

This mutex is initialized but never used.
Remove it.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.com>
Change-Id: Id6fbbfdc5344435627b88104c46785e8d95e4ab1
Reviewed-on: https://review.whamcloud.com/35878
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Arshad Hussain <arshad.super@gmail.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>