dma: rc4030: limit interval timer reload value

The JAZZ RC4030 chipset emulator has a periodic timer and
associated interval reload register. The reload value is used
as divider when computing timer's next tick value. If reload
value is large, it could lead to divide by zero error. Limit
the interval reload value to avoid it.
Reported-by: NHuawei PSIRT <psirt@huawei.com>
Signed-off-by: NPrasad J Pandit <pjp@fedoraproject.org>
Tested-by: NHervé Poussineau <hpoussin@reactos.org>
Signed-off-by: NYongbok Kim <yongbok.kim@imgtec.com>

hw/dma/rc4030.c

@@ -460,7 +460,7 @@ static void rc4030_write(void *opaque, hwaddr addr, uint64_t data,
         break;
     /* Interval timer reload */
     case 0x0228:
-        s->itr = val;
+        s->itr = val & 0x01FF;
         qemu_irq_lower(s->timer_irq);
         set_next_tick(s);
         break;