Make REQUEST_NETWORK_SCORES signature only.

There are no use cases where it's needed by a privileged app today.

Test: Built and ran
BUG: 33752149
Change-Id: Ia63a86eca1f60644d25f037d395a08c541a06a08
Merged-In: Iae689e878fdb60b506536c918079a4fcff527a71
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 7cf11d4..048214a 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -1236,7 +1236,7 @@
          recommendations and scores from the NetworkScoreService.
          <p>Not for use by third-party applications. @hide -->
     <permission android:name="android.permission.REQUEST_NETWORK_SCORES"
-        android:protectionLevel="signature|privileged" />
+        android:protectionLevel="signature" />
 
     <!-- ======================================= -->
     <!-- Permissions for short range, peripheral networks -->