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.

Fixes: 770c69f ("interconnect: Add debugfs test client")
Signed-off-by: Georgi Djakov <djakov@kernel.org>
Reviewed-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Tested-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Link: https://lore.kernel.org/r/20260109122523.125843-1-djakov@kernel.org
Signed-off-by: Georgi Djakov <djakov@kernel.org>

Author: Georgi Djakov

drivers/interconnect/debugfs-client.c

@@ -150,6 +150,11 @@ int icc_debugfs_client_init(struct dentry *icc_dir)
 		return ret;
 	}
 
+	src_node = devm_kstrdup(&pdev->dev, "", GFP_KERNEL);
+	dst_node = devm_kstrdup(&pdev->dev, "", GFP_KERNEL);
+	if (!src_node || !dst_node)
+		return -ENOMEM;
+
 	client_dir = debugfs_create_dir("test_client", icc_dir);
 
 	debugfs_create_str("src_node", 0600, client_dir, &src_node);