[cleanup] Remove unnecessary inline JSHint config

- Ember is imported below so we don’t need the global 😄
- The `eqnull:true` rule was originally added for
beb2f26
050fd7b but was later added to the `.jshintrc` in
caa2753
3ed8fd7?diff=unified

(cherry picked from commit 67c4bc8)

addon/-private/system/store.js

@@ -1,6 +1,3 @@
-/*globals Ember*/
-/*jshint eqnull:true*/
-
 /**
   @module ember-data
 */