bhyve nvme: Add NQN value

Add a NVMe Qualified Name (NQN) to the Controller Data structure using
the "first format" (i.e., "... used by any organization that owns a
domain name" Section 7.9 NVM-Express 1.4c 2021.06.28 Ratified).

This avoids a Linux kernel warning about a missing or invalid NQN.

Reviewed by: jhb
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D42058