Added option for num keypad for YubiKey

OpenKeychain/src/main/res/xml/adv_preferences.xml

@@ -44,5 +44,9 @@
         android:defaultValue="true"
         android:title="@string/label_use_default_yubikey_pin"
         android:summary="@string/label_label_use_default_yubikey_pin_summary" />
-
+    <CheckBoxPreference
+        android:key="useNumKeypadForYubikeyPin"
+        android:persistent="false"
+        android:defaultValue="false"
+        android:title="@string/label_use_num_keypad_for_yubikey_pin" />
 </PreferenceScreen>