We had gotten a bit sloppy with the workqueue flags. We needed _UNBOUND
in some workqueues where we wanted concurrency by scheduling across cpus
instead of waiting for the current (very long running) work on a cpu to
finish. We add NON_REENTRANT out of an abundance of caution. It has
gone away in modern kernels and is probably not needed here, but
according to the docs we would want it so we at least document that fact
by using it.
Signed-off-by: Zach Brown <zab@versity.com>