LU-9679 llite: use lli_flags instead of lli_update_atime

LU-9679 llite: use lli_flags instead of lli_update_atime

Rather than adding a new single-bit field for a flag, use the
already-existing lli_flags field.

Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I23abc5c7c7383dca3385958f804074baaf551567
Reviewed-on: https://review.whamcloud.com/36839
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Nikitas Angelinas <nangelinas@cray.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>