audio policy: register effect CPU on enable

Added a method on audio policy interface to register
audio effect CPU usage on enable and unregister on disable
instead of when the effect is created or destroyed.

Change-Id: Iee20bf70fee7302f817ec4c7d9bf7640caca2e95
diff --git a/modules/audio/audio_policy.c b/modules/audio/audio_policy.c
index 58dae3e..409f0a1 100644
--- a/modules/audio/audio_policy.c
+++ b/modules/audio/audio_policy.c
@@ -196,6 +196,11 @@
     return -ENOSYS;
 }
 
+static int ap_set_effect_enabled(struct audio_policy *pol, int id, bool enabled)
+{
+    return -ENOSYS;
+}
+
 static bool ap_is_stream_active(const struct audio_policy *pol, int stream,
                                 uint32_t in_past_ms)
 {
@@ -250,6 +255,7 @@
     dap->policy.get_output_for_effect = ap_get_output_for_effect;
     dap->policy.register_effect = ap_register_effect;
     dap->policy.unregister_effect = ap_unregister_effect;
+    dap->policy.set_effect_enabled = ap_set_effect_enabled;
     dap->policy.is_stream_active = ap_is_stream_active;
     dap->policy.dump = ap_dump;