autojson: handle recursion

In order to allow the configurations directory to have vendor
subdirectories, modify the script slightly for directory traversal
to handle subdirectories.

Tested:

After performing a `git mv`, the subdirectory files show up in the
`format-code` output.
```
...
formatting file configurations/meta/terminus_2x100g_nic_tsff.json
...
```

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib8cea8053d558c60e0a89dd6dcddbc4bc0d970fb
diff --git a/scripts/autojson.py b/scripts/autojson.py
index afbe696..263336e 100755
--- a/scripts/autojson.py
+++ b/scripts/autojson.py
@@ -87,13 +87,15 @@
         return "\n".join(result)
 
 
-files = argv[1:]
+files = []
 
-for file in files[:]:
-    if os.path.isdir(file):
-        files.remove(file)
-        for f in os.listdir(file):
-            files.append(os.path.join(file, f))
+for file in argv[1:]:
+    if not os.path.isdir(file):
+        files.append(file)
+        continue
+    for root, _, filenames in os.walk(file):
+        for f in filenames:
+            files.append(os.path.join(root, f))
 
 for file in files:
     if not file.endswith(".json"):