btrfs: abort transaction on failure to add link to inode

If we fail to update the inode or delete the orphan item, we must abort
the transaction to prevent persisting an inconsistent state. For example
if we fail to update the inode item, we have the inconsistency of having
a persisted inode item with a link count of N but we have N + 1 inode ref
items and N + 1 directory entries pointing to our inode in case the
transaction gets committed.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>