Revert "wfd: release wifi p2p resource on disconnecting from WFD service."

This reverts commit fa0aeee678700b7f9865c06ec45d9d3a6e31089f.
Reason for revert: during the disconnection, there are still codes using WifiP2pService.

Bug: 184504089
Test: execute "adb shell setprop persist.debug.wfd.enable 1" and restart the DUT
Change-Id: I0f5a31e072e31fb10f0efe667caa6a6d85942867
diff --git a/services/core/java/com/android/server/display/WifiDisplayController.java b/services/core/java/com/android/server/display/WifiDisplayController.java
index 6db75eb..a7e1a28 100644
--- a/services/core/java/com/android/server/display/WifiDisplayController.java
+++ b/services/core/java/com/android/server/display/WifiDisplayController.java
@@ -550,11 +550,6 @@
 
     private void disconnect() {
         mDesiredDevice = null;
-        mWifiP2pManager = null;
-        if (null != mWifiP2pChannel) {
-            mWifiP2pChannel.close();
-            mWifiP2pChannel = null;
-        }
         updateConnection();
     }