Use colorful +s

Instead of grey

Change-Id: Iac0454110d3af9045a83098e67957130987ad718
Fixes: 63820885
Test: manual

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

@@ -402,7 +402,7 @@ public class FingerprintSettings extends SubSettings {
             Preference addPreference = new Preference(root.getContext());
             addPreference.setKey(KEY_FINGERPRINT_ADD);
             addPreference.setTitle(R.string.fingerprint_add_title);
-            addPreference.setIcon(R.drawable.ic_add_24dp);
+            addPreference.setIcon(R.drawable.ic_menu_add);
             root.addPreference(addPreference);
             addPreference.setOnPreferenceChangeListener(this);
             updateAddPreference();