Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/d6b0691491e1
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Merge pull request #25533 from pivanov/bug-1089567

Bug 1089567 - [gallery] remove unused play button background images

========

https://hg.mozilla.org/integration/gaia-central/rev/3dd3a00ad4d1
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 1089567 - [gallery] remove unused play button background images

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "641fa70735be0abcf817d4a86e7ae17d5596c816", 
+    "revision": "d6b0691491e190e662d64b46c70fe35c69ae8704", 
     "repo_path": "/integration/gaia-central"
 }