hw/char/max78000_uart: Destroy FIFO on deinit

In the max78000_uart we create a FIFO in the instance_init function,
but we don't destroy it on deinit, so ASAN reports a leak in the
device-introspect-test:

    #0 0x561cc92d5de3 in malloc (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/arm-asan/qemu-system-arm+0x21f1de3) (BuildId: 98fdf9fc85c3beaeca8eda0be8412f1e11b9c6ad)
    #1 0x70cbf2afab09 in g_malloc (/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x62b09) (BuildId: 1eb6131419edb83b2178b682829a6913cf682d75)
    #2 0x561ccc4c884d in fifo8_create /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/arm-asan/../../util/fifo8.c:27:18
    #3 0x561cc9744ec9 in max78000_uart_init /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/arm-asan/../../hw/char/max78000_uart.c:241:5

Add an instance_finalize method to destroy the FIFO.

Cc: qemu-stable@nongnu.org
Fixes: d447e4b702 ("MAX78000: UART Implementation")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250821154358.2417744-1-peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

hw/char/max78000_uart.c

@@ -247,6 +247,12 @@ static void max78000_uart_init(Object *obj)
     sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
 }
 
+static void max78000_uart_finalize(Object *obj)
+{
+    Max78000UartState *s = MAX78000_UART(obj);
+    fifo8_destroy(&s->rx_fifo);
+}
+
 static void max78000_uart_realize(DeviceState *dev, Error **errp)
 {
     Max78000UartState *s = MAX78000_UART(dev);
@@ -274,6 +280,7 @@ static const TypeInfo max78000_uart_info = {
     .parent        = TYPE_SYS_BUS_DEVICE,
     .instance_size = sizeof(Max78000UartState),
     .instance_init = max78000_uart_init,
+    .instance_finalize = max78000_uart_finalize,
     .class_init    = max78000_uart_class_init,
 };