Fix icon margins for leanback preference items.

Change-Id: I9fb60b1b23903dac61e9f7d909e0ce2c0343c07b
diff --git a/v17/preference-leanback/res/layout/leanback_preference.xml b/v17/preference-leanback/res/layout/leanback_preference.xml
index 85baff3..498b107 100644
--- a/v17/preference-leanback/res/layout/leanback_preference.xml
+++ b/v17/preference-leanback/res/layout/leanback_preference.xml
@@ -36,7 +36,7 @@
             android:id="@android:id/icon"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:layout_gravity="center"
+            android:layout_marginEnd="@dimen/lb_preference_item_icon_margin_end"
             />
     </FrameLayout>