hw/arm_mptimer: Reset the qemu_timer at reset

On reset of the mpcore timer/watchdog block we need to
delete the qemu_timer in case it was running.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/arm_mptimer.c

diff --git a/hw/arm_mptimer.c b/hw/arm_mptimer.c
index df7fb4c..fe43cbb 100644
--- a/hw/arm_mptimer.c
+++ b/hw/arm_mptimer.c
@@ -228,6 +228,9 @@
     tb->control = 0;
     tb->status = 0;
     tb->tick = 0;
+    if (tb->timer) {
+        qemu_del_timer(tb->timer);
+    }
 }
 
 static void arm_mptimer_reset(DeviceState *dev)