Kernel: Write to debug log when creating new kmalloc subheaps

Kernel/Heap/kmalloc.cpp

@@ -55,6 +55,7 @@ struct KmallocGlobalData {
 
     void add_subheap(u8* storage, size_t storage_size)
     {
+        dbgln("Adding kmalloc subheap @ {} with size {}", storage, storage_size);
         auto* subheap = new (storage) KmallocSubheap(storage + PAGE_SIZE, storage_size - PAGE_SIZE);
         subheaps.append(*subheap);
     }