qcacld-3.0: Remove wlan_serialization_legacy_init_callback

Each cmd in serialization list holds a vdev ref by
I8d573ff5a25e6dff928b2708e51ad7b97e292277. When vdev is
destroyed physically, it means vdev ref count is 0, all
serialization cmds of this vdev are released, so no need
to registed purge calback.

Change-Id: Iea75707c88154e1e3e87369285b82d1288523e22
CRs-Fixed: 2373677

core/sme/src/common/sme_api.c

@@ -762,7 +762,6 @@ QDF_STATUS sme_open(mac_handle_t mac_handle)
 	}
 	sme_trace_init(mac);
 	sme_register_debug_callback();
-	wlan_serialization_legacy_init_callback();
 
 	return status;
 }