btrfs: rename device free rcu helper to free_device_rcu

Make it clear that it is an RCU helper, we want to use the name
free_device for a wrapper freeing all device members.

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2017-06-06 17:08:23 +02:00
commit f06c5965ab