btrfs-progs: do not add stale device into fs_devices

btrfs-progs: do not add stale device into fs_devices

If one of btrfs' devices was pulled out and we've replaced it with a
new one, then they have the same uuid.

If that device gets reconnected, 'btrfs filesystem show' will show the
stale one instead of the new one, but on the kernel side btrfs has a fix
not to include the stale one, this could confuse users as people may
monitor btrfs by running that command.

This does the similar thing to what kernel side has done.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
[ format string adjustments ]
Signed-off-by: David Sterba <dsterba@suse.com>