service: Resolve cases of member field shadowing

Now all that remains is for kernel code to be 'shadow-free' and then
-Wshadow can be turned into an error.

src/core/hle/service/hid/controllers/npad.h

@@ -26,7 +26,7 @@ constexpr u32 NPAD_UNKNOWN = 16; // TODO(ogniK): What is this?
 
 class Controller_NPad final : public ControllerBase {
 public:
-    explicit Controller_NPad(Core::System& system);
+    explicit Controller_NPad(Core::System& system_);
     ~Controller_NPad() override;
 
     // Called when the controller is initialized