LU-16695 llite: switch to ki_flags from f_flags

LU-16695 llite: switch to ki_flags from f_flags

There are possible races between IO checking f_flags and
fcntl changing f_flags.  The kernel fixed most of these by
copying most of the file flags in to the iocb.

Let's follow on and use those copied flags.  This also lets
us change them if we want, since they're now local to the
specific IO.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Signed-off-by: Guillaume Courrier <guillaume.courrier@cea.fr>
Change-Id: Ib98cccec0e7888865ec10dc5f76f1d9917a1aef7
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50493
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Etienne AUJAMES <eaujames@ddn.com>