LU-7853 lod: fixes bitfield in lod qos code

LU-7853 lod: fixes bitfield in lod qos code

Updating bitfields in struct lod_qos struct is protected
by lq_rw_sem in most places but an update can be lost
due unprotected bitfield access from
lod_qos_thresholdrr_seq_write() and qos_prio_free_store().
This patch fixes it by replacing bitfields with named bits
and atomic bitops.

Cray-bug-id: LUS-4651
Signed-off-by: Rahul Deshmukh <rahul.deshmukh@seagate.com>
Signed-off-by: Alexander Zarochentsev <c17826@cray.com>
Change-Id: I28299ce4960e91be551d7f6e43a3b598daf4d7a2
Reviewed-on: https://review.whamcloud.com/18812
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alexander Zarochentsev <alexander.zarochentsev@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>