ba405bc811
This allows create/delete/attach/detach namespaces on new NVMe controllers. This is only a first user-level part of the bigger change set. Kernel part required to detect and handle the configuration changes without reboot is completely independent and will be added separately. Submitted by: Matt Williams <mffbsdw@gmail.com> (original version) Differential Revision: https://reviews.freebsd.org/D11399