hw/char/exynos4210_uart: Fix memleaks in exynos4210_uart_init

It's easy to reproduce as follow:
virsh qemu-monitor-command vm1 --pretty '{"execute": "device-list-properties",
"arguments":{"typename":"exynos4210.uart"}}'

ASAN shows memory leak stack:
  64kramsystem#1 0xfffd896d71cb in g_malloc0 (/lib64/libglib-2.0.so.0+0x571cb)
  64kramsystem#2 0xaaad270beee3 in timer_new_full /qemu/include/qemu/timer.h:530
  64kramsystem#3 0xaaad270beee3 in timer_new /qemu/include/qemu/timer.h:551
  64kramsystem#4 0xaaad270beee3 in timer_new_ns /qemu/include/qemu/timer.h:569
  64kramsystem#5 0xaaad270beee3 in exynos4210_uart_init /qemu/hw/char/exynos4210_uart.c:677
  64kramsystem#6 0xaaad275c8f4f in object_initialize_with_type /qemu/qom/object.c:516
  64kramsystem#7 0xaaad275c91bb in object_new_with_type /qemu/qom/object.c:684
  64kramsystem#8 0xaaad2755df2f in qmp_device_list_properties /qemu/qom/qom-qmp-cmds.c:152

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20200213025603.149432-1-kuhn.chenqun@huawei.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/char/exynos4210_uart.c

@@ -674,8 +674,6 @@ static void exynos4210_uart_init(Object *obj)
     SysBusDevice *dev = SYS_BUS_DEVICE(obj);
     Exynos4210UartState *s = EXYNOS4210_UART(dev);
 
-    s->fifo_timeout_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
-                                         exynos4210_uart_timeout_int, s);
     s->wordtime = NANOSECONDS_PER_SECOND * 10 / 9600;
 
     /* memory mapping */
@@ -691,6 +689,9 @@ static void exynos4210_uart_realize(DeviceState *dev, Error **errp)
 {
     Exynos4210UartState *s = EXYNOS4210_UART(dev);
 
+    s->fifo_timeout_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
+                                         exynos4210_uart_timeout_int, s);
+
     qemu_chr_fe_set_handlers(&s->chr, exynos4210_uart_can_receive,
                              exynos4210_uart_receive, exynos4210_uart_event,
                              NULL, s, NULL, true);