IPCHLE: improve HLE timing.

This change attempts to make calls to WII_IPC_HLE_Interface::Update()
more consistent.  We should be calling it whenever there is something we
can pop from a queue, and this patch does that.

DeviceUpdate() now works independently of Update(): it's now just a periodic
timer for devices which need to regularly update state.

With this change, we need a non-zero default delay for IPC replies because
replies are popped off the queue much more aggressively.

This fixes launching channels from the the System Menu.

Source/Core/Core/HW/SystemTimers.cpp

@@ -165,7 +165,7 @@ void IPC_HLE_UpdateCallback(u64 userdata, int cyclesLate)
 {
 	if (SConfig::GetInstance().m_LocalCoreStartupParameter.bWii)
 	{
-		WII_IPC_HLE_Interface::Update();
+		WII_IPC_HLE_Interface::UpdateDevices();
 		CoreTiming::ScheduleEvent(IPC_HLE_PERIOD - cyclesLate, et_IPC_HLE);
 	}
 }