Ship Hardware Platform Extension API in Beta

Bug: 860311
Change-Id: Id41234cfd6337fd2dcdd319fc514f9ae7663c6a4
Reviewed-on: https://chromium-review.googlesource.com/1211724Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589282}

chrome/common/extensions/api/_permission_features.json

@@ -293,7 +293,7 @@
     "location": "policy"
   },
   "enterprise.hardwarePlatform": {
-    "channel": "canary",
+    "channel": "beta",
     "extension_types": ["extension"],
     "location": "policy"
   },