Remove dark dividers in tablet portrait

The dividers were being set null in the normal styles,
but not in sw600dp-port.

Bug: 17508993
Change-Id: Ibfafa26f5e0cc31c175c8a0a914f32c8401a4dab
diff --git a/res/values-sw600dp-port/styles.xml b/res/values-sw600dp-port/styles.xml
index 257e86c..29016fa 100644
--- a/res/values-sw600dp-port/styles.xml
+++ b/res/values-sw600dp-port/styles.xml
@@ -25,5 +25,6 @@
         <item name="android:paddingTop">@dimen/two_pane_tl_top</item>
         <item name="android:paddingBottom">@dimen/two_pane_tl_top</item>
         <item name="android:clipToPadding">false</item>
+        <item name="android:divider">@null</item>
     </style>
 </resources>