arch/sim: add host_set_timeratio stub for Windows

The simulated time ratio feature introduced a host_set_timeratio()
call in sim_head.c, but the Windows host time implementation was
missing this symbol, causing a link error. Add a no-op stub since
the time ratio feature is not implemented on Windows.

Signed-off-by: Lingao Meng <menglingao@xiaomi.com>

arch/sim/src/sim/win/sim_hosttime.c

@@ -150,6 +150,22 @@ int host_settimer(uint64_t nsec)
   return -ENOSYS;
 }
 
+/****************************************************************************
+ * Name: host_set_timeratio
+ *
+ * Description:
+ *   Set the ratio of simulated time to real time in percent.
+ *   Not implemented on Windows.
+ *
+ * Input Parameters:
+ *   ratio - The new time ratio in percent
+ *
+ ****************************************************************************/
+
+void host_set_timeratio(int ratio)
+{
+}
+
 /****************************************************************************
  * Name: host_timerirq
  *