LU-9859 lustre: remove current_pid() and current_comm()

LU-9859 lustre: remove current_pid() and current_comm()

Just use current->pid and current->comm directly, instead
of having wrappers.

Linux-commit: 63fd7d04580b6345ff1e0aab906c034f973d493e

Test-Parameters: trivial
Change-Id: I278f32d6dd8c370a7ab211c5147ee8d246ea1893
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-on: https://review.whamcloud.com/37776
Reviewed-by: Neil Brown <neilb@suse.de>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>