Ensure "vibrate in silent" box is never disabled.

Should complete the decoupling work started in change
I724c43aa4f5b1a12b95097381844a47c5dcf1e0d.

Change-Id: I3bad426534533149879fb098533a223cdcdb4d72
diff --git a/src/com/android/settings/SoundSettings.java b/src/com/android/settings/SoundSettings.java
index c1f773c..ca7a1f3 100644
--- a/src/com/android/settings/SoundSettings.java
+++ b/src/com/android/settings/SoundSettings.java
@@ -183,7 +183,6 @@
             mSilent.setChecked(silentOrVibrateMode);
         }
 
-        mVibrateInSilent.setEnabled(silentOrVibrateMode);
         mVibrateInSilent.setChecked(Settings.System.getInt(
             getContentResolver(),
             Settings.System.VIBRATE_IN_SILENT,