Removed WIP tag from Neuralnetworks HAL

Additionally cleaned up some comments and formatting.

Bug: 63905942
Test: not needed
Change-Id: I0306f6d37f3c9ce9b365b5f838c27e81fa001ccd
diff --git a/neuralnetworks/1.0/IPreparedModel.hal b/neuralnetworks/1.0/IPreparedModel.hal
index a7c3342..5df883e 100644
--- a/neuralnetworks/1.0/IPreparedModel.hal
+++ b/neuralnetworks/1.0/IPreparedModel.hal
@@ -36,11 +36,16 @@
      *
      * @param request The input and output information on which the prepared
      *                model is to be executed.
-     *                prepared model.
      * @param event A callback used for synchronization that must be signaled
      *              once the execution has finished.
-     * @return status ErrorStatus::NONE if the asynchronous task was
-     *                successfully launched.
+     * @return status Error status of the call, must be:
+     *                - NONE if task is successfully launched
+     *                - DEVICE_UNAVAILABLE if driver is offline or busy
+     *                - GENERAL_FAILURE if there is an unspecified error
+     *                - OUTPUT_INSUFFICIENT_SIZE if provided output buffer is
+     *                  not large enough to store the resultant values
+     *                - INVALID_ARGUMENT when one of the input arguments is
+     *                  invalid
      */
     execute(Request request, IEvent event) generates (ErrorStatus status);
 };