Revert "Let InputFlinger create the server InputChannel"

Revert submission 12594832-hide_server_input_channel

Reason for revert: <INSERT REASONING HERE>
Reverted Changes:
I7033caf10:Use new create/removeInputChannel().
I35f768c8a:Let InputFlinger create the server InputChannel

Bug: 169083114
Bug: 169088136
Change-Id: Ib6945129936006682cd03cea614fbdfd4f5fa008
diff --git a/libs/input/android/os/IInputFlinger.aidl b/libs/input/android/os/IInputFlinger.aidl
index 1771d19..0cdf0bb 100644
--- a/libs/input/android/os/IInputFlinger.aidl
+++ b/libs/input/android/os/IInputFlinger.aidl
@@ -30,8 +30,8 @@
     // shouldn't be a concern.
     oneway void setInputWindows(in InputWindowInfo[] inputHandles,
             in @nullable ISetInputWindowsListener setInputWindowsListener);
-    InputChannel createInputChannel(in @utf8InCpp String name);
-    void removeInputChannel(in IBinder connectionToken);
+    void registerInputChannel(in InputChannel channel);
+    void unregisterInputChannel(in IBinder connectionToken);
     /**
      * Sets focus to the window identified by the token. This must be called
      * after updating any input window handles.