MD Settings: Make links inside disabled checkbox clickable on syncSetup page

BUG=621903
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2563443005
Cr-Commit-Position: refs/heads/master@{#437597}

chrome/browser/resources/settings/people_page/sync_page.html

@@ -44,6 +44,10 @@
           padding: 0;
         };
       }
+
+      #paymentLearnMore {
+        pointer-events: initial;
+      }
     </style>
     <div id="[[pages.SPINNER]]" class="settings-box first"
         hidden$="[[!isStatus_(pages.SPINNER, pageStatus_)]]">