Keystore needs to be able to call apps

The ConfirmationUI API has a callback interface by which confirmation
results are presented to the calling app. This requires keystore to call
into apps.

Test: Device boots and no more denials when call back is delivered to
      apps.
Bug: 63928580
Change-Id: Ie23211aeb74c39956c3c3b8b32843d35afa1315a

public/te_macros

@@ -560,6 +560,7 @@ define(`use_keystore', `
   allow keystore $1:process getattr;
   allow $1 keystore_service:service_manager find;
   binder_call($1, keystore)
+  binder_call(keystore, $1)
 ')
 
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