Fix Clear Credentials item

This should be enabled whenever there is a credential in the keystore
since there can be unencrypted credentials in there now.

Bug: 8651830
Change-Id: I52a8262011d744d782b35d97deaabcba3b23f32b
diff --git a/src/com/android/settings/SecuritySettings.java b/src/com/android/settings/SecuritySettings.java
index c324dd8..e97c73f 100644
--- a/src/com/android/settings/SecuritySettings.java
+++ b/src/com/android/settings/SecuritySettings.java
@@ -452,7 +452,7 @@
         }
 
         if (mResetCredentials != null) {
-            mResetCredentials.setEnabled(!mKeyStore.isUnlocked());
+            mResetCredentials.setEnabled(!mKeyStore.isEmpty());
         }
     }