Don't remove md devices with standard names.

Don't remove md devices with standard names.

If udev is not in use, we create device in /dev when assembling
arrays and remove them when stopping the array.

However it may not always be correct to remove the device.  If
the array was started with kernel auto-detect, them mdadm didn't
create anything and so shouldn't remove anything.

We don't record whether we created things, so just don't remove
anything with a 'standard' name.  Only remove symlinks to the
standard name as we almost certainly created those.

Reported-by: Petre Rodan <petre.rodan@avira.com>
Signed-off-by: NeilBrown <neilb@suse.de>