bcachefs: Delete dead code

The interior btree node update path has changed, this is no longer
needed.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_update_interior.c

@@ -1384,9 +1384,6 @@ void bch2_btree_insert_node(struct btree_update *as, struct btree *b,
 	BUG_ON(!as || as->b);
 	bch2_verify_keylist_sorted(keys);
 
-	if (as->must_rewrite)
-		goto split;
-
 	bch2_btree_node_lock_for_insert(c, b, iter);
 
 	if (!bch2_btree_node_insert_fits(c, b, bch2_keylist_u64s(keys))) {

fs/bcachefs/btree_update_interior.h

@@ -47,7 +47,6 @@ struct btree_update {
 		BTREE_INTERIOR_UPDATING_AS,
 	} mode;
 
-	unsigned			must_rewrite:1;
 	unsigned			nodes_written:1;
 
 	enum btree_id			btree_id;