hw/audio/ac97: Use the QOM DEVICE() macro to access DeviceState.qdev

Rather than looking inside the definition of a DeviceState with
"s->qdev", use the QOM prefered style: "DEVICE(s)".

This patch was generated using the following Coccinelle script
(with a bit of manual fix-up, removing an extra space to please
checkpatch.pl):

    // Use DEVICE() macros to access DeviceState.qdev
    @use_device_macro_to_access_qdev@
    expression obj;
    identifier dev;
    @@
    -&obj->dev.qdev
    +DEVICE(obj)
Suggested-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>.
Message-Id: <20190528164020.32250-7-philmd@redhat.com>
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>

hw/audio/ac97.c

@@ -1388,7 +1388,7 @@ static void ac97_realize(PCIDevice *dev, Error **errp)
     pci_register_bar (&s->dev, 0, PCI_BASE_ADDRESS_SPACE_IO, &s->io_nam);
     pci_register_bar (&s->dev, 1, PCI_BASE_ADDRESS_SPACE_IO, &s->io_nabm);
     AUD_register_card ("ac97", &s->card);
-    ac97_on_reset (&s->dev.qdev);
+    ac97_on_reset(DEVICE(s));
 }
 
 static void ac97_exit(PCIDevice *dev)