bcachefs: Fix a bug with multiple iterators being traversed

If upgrade fails on one iterator, but it was copied from another
iterator and will be freed before transaction restart, then the original
iterator will get traversed first, so we need to make required btree
nodes on the original iterator will be traversed too.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.c

@@ -320,7 +320,6 @@ bool __bch2_btree_iter_upgrade(struct btree_iter *iter,
 	trans_for_each_iter(iter->trans, linked)
 		if (linked != iter &&
 		    linked->btree_id == iter->btree_id &&
-		    btree_iter_cmp(linked, iter) <= 0 &&
 		    linked->locks_want < new_locks_want) {
 			linked->locks_want = new_locks_want;
 			btree_iter_get_locks(linked, true);