cmake: Add Qemu NVMe emulated device

As it is meant to be used on the tests/drivers/disk test case, it will
currently create a dummy 1Mb image on a fixed path to serve as a NVMe
disk.

It could be made of an alternate path and size, if necessary.

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