InputCommon: cleanup warnings of -Wclass-memaccess

Initialize m_state with the default constructor.

Source/Core/InputCommon/ControllerInterface/Xlib/XInput2.cpp

@@ -131,8 +131,6 @@ void KeyboardMouse::SelectEventsForDevice(Window window, XIEventMask* mask, int
 KeyboardMouse::KeyboardMouse(Window window, int opcode, int pointer, int keyboard)
     : m_window(window), xi_opcode(opcode), pointer_deviceid(pointer), keyboard_deviceid(keyboard)
 {
-  memset(&m_state, 0, sizeof(m_state));
-
   // The cool thing about each KeyboardMouse object having its own Display
   // is that each one gets its own separate copy of the X11 event stream,
   // which it can individually filter to get just the events it's interested

Source/Core/InputCommon/ControllerInterface/Xlib/XInput2.h

@@ -105,7 +105,7 @@ public:
 private:
   Window m_window;
   Display* m_display;
-  State m_state;
+  State m_state{};
   int xi_opcode;
   const int pointer_deviceid, keyboard_deviceid;
   std::string name;