tests/disk: Add NVMe disk to disk_performance

On Qemu x86_64 it is possible to emulate an NVMe controller and disk on
the PCIe bus, so let's add this case here to verify how the newly added
NVMe controller and disk driver perform, relatively to the host.
This will prove to be useful to evaluate the optimization to be made, or
the possible regression that could happen on future changes.

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>