interconnect: debugfs: initialize src_node and dst_node to empty strings

In the Linux kernel, the following vulnerability has been resolved: interconnect: debugfs: initialize src_node and dst_node to empty strings The debugfs_create_str() API assumes that the string pointer is either NULL or points to valid kmalloc() memory. Leaving the pointer uninitialized can cause problems. Initialize src_node and dst_node to empty strings before creating the debugfs entries to guarantee that reads and writes are safe.