arm_mptimer: Respect IT bit state

The timer should fire the interrupt only if the IT (interrupt enable) bit
state of the control register is enabled.
Signed-off-by: NDmitry Osipenko <digetx@gmail.com>
Reviewed-by: NPeter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/timer/arm_mptimer.c

@@ -38,7 +38,7 @@ static inline int get_current_cpu(ARMMPTimerState *s)
 
 static inline void timerblock_update_irq(TimerBlock *tb)
 {
-    qemu_set_irq(tb->irq, tb->status);
+    qemu_set_irq(tb->irq, tb->status && (tb->control & 4));
 }
 
 /* Return conversion factor from mpcore timer ticks to qemu timer ticks.  */