[PATCH blktests] nvme/rc: fix nvme device readiness check after _nvme_connect_subsys

[Sagi Grimberg]

> The helper function _nvme_connect_subsys() creates a nvme device. It may
> take some time after the function call until the device gets ready for
> I/O. So it is expected that the test cases call _find_nvme_dev() after
> _nvme_connect_subsys() before I/O. _find_nvme_dev() returns the path of
> the created device, and it also waits for uuid and wwid sysfs attributes
> of the created device get ready. This wait works as the wait for the
> device I/O readiness.

Shouldn't this call udevadm --settle or something?