Replace magic disconnect channel number with a constant

Source/Core/Core/HW/Wiimote.h

@@ -63,6 +63,8 @@ enum class InitializeMode
 
 // The Real Wii Remote sends report every ~5ms (200 Hz).
 constexpr int UPDATE_FREQ = 200;
+// Custom channel ID used in ControlChannel to indicate disconnects
+constexpr int DOLPHIN_DISCONNET_CONTROL_CHANNEL = 99;
 
 void Shutdown();
 void Initialize(InitializeMode init_mode);

Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.cpp

@@ -572,7 +572,7 @@ void Wiimote::SendDataReport()
 void Wiimote::ControlChannel(const u16 channel_id, const void* data, u32 size)
 {
   // Check for custom communication
-  if (99 == channel_id)
+  if (channel_id == ::Wiimote::DOLPHIN_DISCONNET_CONTROL_CHANNEL)
   {
     // Wii Remote disconnected.
     Reset();

Source/Core/Core/HW/WiimoteReal/WiimoteReal.cpp

@@ -143,7 +143,7 @@ void Wiimote::ClearReadQueue()
 void Wiimote::ControlChannel(const u16 channel, const void* const data, const u32 size)
 {
   // Check for custom communication
-  if (channel == 99)
+  if (channel == ::Wiimote::DOLPHIN_DISCONNET_CONTROL_CHANNEL)
   {
     if (m_really_disconnect)
     {

Source/Core/Core/IOS/USB/Bluetooth/WiimoteDevice.cpp

@@ -218,7 +218,8 @@ void WiimoteDevice::EventConnectionAccepted()
 void WiimoteDevice::EventDisconnect()
 {
   // Send disconnect message to plugin
-  Wiimote::ControlChannel(m_connection_handle & 0xFF, 99, nullptr, 0);
+  Wiimote::ControlChannel(m_connection_handle & 0xFF, Wiimote::DOLPHIN_DISCONNET_CONTROL_CHANNEL,
+                          nullptr, 0);
 
   m_connection_state = ConnectionState::Inactive;