bdk: heap: add zalloc and utilize it

bdk/mem/heap.h

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2018 naehrwert
- * Copyright (c) 2018-2020 CTCaer
+ * Copyright (c) 2018-2024 CTCaer
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -48,6 +48,7 @@ void heap_init(void *base);
 void heap_set(heap_t *heap);
 void *malloc(u32 size);
 void *calloc(u32 num, u32 size);
+void *zalloc(u32 size);
 void free(void *buf);
 void heap_monitor(heap_monitor_t *mon, bool print_node_stats);