Fix crash in Settings on devices without fingerprint.

Fixes bug 27060816

Change-Id: I3b45d3bfa6e47abb4a43ca95c15fd3614f9478dd

src/com/android/settings/fingerprint/FingerprintUiHelper.java

@@ -49,7 +49,7 @@ public class FingerprintUiHelper extends FingerprintManager.AuthenticationCallba
     }
 
     public void startListening() {
-        if (mFingerprintManager != null
+        if (mFingerprintManager != null && mFingerprintManager.isHardwareDetected()
                 && mFingerprintManager.getEnrolledFingerprints(mUserId).size() > 0) {
             mCancellationSignal = new CancellationSignal();
             mFingerprintManager.setActiveUser(mUserId);