autojson: don't check non-json files

Skip files that don't have a json suffix so other files (like makefiles)
can be placed in the configurations directory.

Change-Id: Ibdb4d29a6a024762d3f90ca410d11815fe641070
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/scripts/autojson.py b/scripts/autojson.py
index 6b14bd5..1a499df 100755
--- a/scripts/autojson.py
+++ b/scripts/autojson.py
@@ -15,6 +15,8 @@
             files.append(os.path.join(file, f))
 
 for file in files:
+    if not file.endswith('.json'):
+        continue
     print("formatting file {}".format(file))
     with open(file) as f:
         j = json.load(f)