LU-13742 llite: do not bypass selinux xattr handling

LU-13742 llite: do not bypass selinux xattr handling

Without the hint from selinux_is_enabled() to determine if selinux
is running at boot the performance fix from LU-549 to skip handling
of selinux xattrs cannot be correctly handled.

The correct path is to act is if selinux is enabled.

This fixes a bug introduced by LU-12355 that now exists in
RHEL 8.2 kernels where clients have enabled selinux.

Lustre-change: https://review.whamcloud.com/39569
Lustre-commit: 994287bd47819ebd8badb716da4232cdff97d324

Fixes: 39e5bfa734 ("LU-12355 llite: include file linux/selinux.h removed")
Test-Parameters: clientdistro=el8.2 serverdistro=el8.2 clientselinux testlist=sanity-selinux
Test-Parameters: clientdistro=el8.1 serverdistro=el8.1 clientselinux testlist=sanity-selinux
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: I6fb5ed9ecdb79545225b5586b90509eb157a355b
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/39671
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>