nodedev: drop DKD_MEDIA_AVAILABLE property check

nodedev: drop DKD_MEDIA_AVAILABLE property check

The access of DKD_MEDIA_AVAILABLE for floppy disks, is mistakenly
protected by a check for ID_CDROM_MEDIA, introduced in:

  commit 10427db77983edfaafec74ec13cc5015bab6aa95
  Author: Ján Tomko <jtomko@redhat.com>
  Date:   Fri Jun 3 16:10:21 2016 +0200

    Only return two values in udevGetUintProperty

Thus the check of DKD_MEDIA_AVAILABLE never run. In practice this didn't
matter since this property is set by the DeviceKit-Disks daemon which
was only around for 3 Fedora releases before being killed off around
F13. Thus we can just remove this legacy property.

Reviewed-by: Laine Stump <laine@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>