btrfs: fix incorrect comparison for delayed refs

When I reworked delayed ref comparison in cf4f0432 ("btrfs: move
->parent and ->ref_root into btrfs_delayed_ref_node"), I made a mistake
and returned -1 for the case where ref1->ref_root was > than
ref2->ref_root.  This is a subtle bug that can result in improper
delayed ref running order, which can result in transaction aborts.

Fixes: cf4f0432 ("btrfs: move ->parent and ->ref_root into btrfs_delayed_ref_node")
CC: stable@vger.kernel.org # 6.10+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>