Fix non-trivial warnings hidden by -isystem

These warnings were hidden by -isystem.

Bug: 31751828
Test: m -j checkbuild
Change-Id: Ibb1aa07a6827fcbd29fc15291fcd90280c0f608d
diff --git a/radio/Radio.cpp b/radio/Radio.cpp
index fa39589..9ddd221 100644
--- a/radio/Radio.cpp
+++ b/radio/Radio.cpp
@@ -117,8 +117,8 @@
 
 
 // Radio
-Radio::Radio(radio_handle_t handle, const sp<RadioCallback>& callback)
-    : mHandle(handle), mCallback(callback)
+Radio::Radio(radio_handle_t /*handle*/, const sp<RadioCallback>& callback)
+    : mCallback(callback)
 {
 }