nvme: don't assume namespace id

nvme: don't assume namespace id

The tests assume that the namespace id is always 1. This might not be
correct in future (e.g. running real targets), thus harden the test by
using the uuid to lookup the correct namespace id.

The passthru test already do this, so it makes also sense to update the
other tests as well.

Signed-off-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>