WifiManager: add WIFI_MODE_NO_LOCKS_HELD

Add a WifiLock mode representing that no locks are held (@hide).

Bug: 28669096
Change-Id: I774d5ff226e7c639812f9735555c8ea1ed6444af
Test: compiles and runtest frameworks-wifi
(cherry picked from commit 3aa6051d62eface42ac7f577d4911c32e4497861)
diff --git a/framework/java/android/net/wifi/WifiManager.java b/framework/java/android/net/wifi/WifiManager.java
index 1cd32b6..bbc3d2f 100644
--- a/framework/java/android/net/wifi/WifiManager.java
+++ b/framework/java/android/net/wifi/WifiManager.java
@@ -561,6 +561,12 @@
     public static final String ACTION_PICK_WIFI_NETWORK = "android.net.wifi.PICK_WIFI_NETWORK";
 
     /**
+     * Internally used Wi-Fi lock mode representing the case were no locks are held.
+     * @hide
+     */
+    public static final int WIFI_MODE_NO_LOCKS_HELD = 0;
+
+    /**
      * In this Wi-Fi lock mode, Wi-Fi will be kept active,
      * and will behave normally, i.e., it will attempt to automatically
      * establish a connection to a remembered access point that is