WifiLegacyHal: Add missing ring buffer callback dereg

Still figuring out how to send this data over the HIDL callback. Adding
this missing wrapper in legacy hal for now.

Bug:33638159
Test: Compiles
Change-Id: Ifce06a796d54e10c582b9896425899a45162a45f
diff --git a/wifi/1.0/default/wifi_legacy_hal.h b/wifi/1.0/default/wifi_legacy_hal.h
index c846fc8..b585314 100644
--- a/wifi/1.0/default/wifi_legacy_hal.h
+++ b/wifi/1.0/default/wifi_legacy_hal.h
@@ -192,6 +192,7 @@
   std::pair<wifi_error, WakeReasonStats> getWakeReasonStats();
   wifi_error registerRingBufferCallbackHandler(
       const on_ring_buffer_data_callback& on_data_callback);
+  wifi_error deregisterRingBufferCallbackHandler();
   std::pair<wifi_error, std::vector<wifi_ring_buffer_status>>
   getRingBuffersStatus();
   wifi_error startRingBufferLogging(const std::string& ring_name,