Fill device serial_num and device_id in NVMe XPT.

It allows to report GEOM::lunid for nda(4) same as for nvd(4). Since
NVMe now allows multiple LUs (namespaces) with multiple paths unique
LU identification is important. The serial_num field is filled same
as before with the controller serial number, while device_id is based
on namespace GUID and/or EUI64 fields as recommended by "NVM Express:
SCSI Translation Reference" and matching nvd(4) at the end.

MFC after: 1 week