lineage-sdk: Update attr.xml for aapt2

*) the sdk is now using aapt2

*) aapt2 is unhappy with "lineage:..." name attribute value format
   (errors with invalid character).
   
*) update in a way that aapt2 is happy with

Change-Id: I96ecc14c4a6de00272a5ad4f513b62f21289ac45

sdk/res/res/values/attrs.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!--
      Copyright (C) 2016 The CyanogenMod Project
+     Copyright (C) 2018 The LineageOS Project
 
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
@@ -14,8 +15,8 @@
      See the License for the specific language governing permissions and
      limitations under the License.
 -->
-<resources xmlns:lineage="http://schemas.android.com/apk/res/lineageos.platform">
-    <declare-styleable name="lineage:SelfRemovingPreference">
+<resources>
+    <declare-styleable name="lineage_SelfRemovingPreference">
         <attr name="requiresPackage" format="string" />
         <attr name="requiresFeature" format="string" />
         <attr name="requiresConfig" format="string" />
@@ -28,7 +29,7 @@
     </declare-styleable>
 
     <!--Settings search providers-->
-    <declare-styleable name="lineage:Searchable">
+    <declare-styleable name="lineage_Searchable">
         <attr name="xmlRes" format="reference" />
     </declare-styleable>