watermark: fix preferences json

Change-Id: Ibe9b00522110ba6c69c0138f9f3609a1405edc49

WaterMark/data/accountpreferences.json

 [
     {
-{{        "category": "image_category}}",
+        "category": "{{image_category}}",
         "type": "Switch",
         "key": "showlogo",
         "title": "{{showlogo_title}}",
@@ -39,7 +39,7 @@
         "mimeType": "*/png,*/jpg,*/jpeg"
     },
     {
-        "category": "{{image_category"),
+        "category": "{{image_category}}",
         "type": "List",
         "key": "markbackground",
         "title": "{{markbackground_title}}",
@@ -167,7 +167,7 @@
         ]
     },
     {
-        "category": "{{ext_category}}",
+        "category": "{{text_category}}",
         "type": "Switch",
         "key": "time",
         "title": "{{time_title}}",