qemuProcessAutoDestroy: Use 'driver' from VM private data

Access the 'driver' struct from the private data rather than the passed
opaque pointer in preparation to remove the opaque pointer.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

src/qemu/qemu_process.c

@@ -8374,10 +8374,10 @@ void qemuProcessStop(virQEMUDriver *driver,
 static void
 qemuProcessAutoDestroy(virDomainObj *dom,
                        virConnectPtr conn,
-                       void *opaque)
+                       void *opaque G_GNUC_UNUSED)
 {
-    virQEMUDriver *driver = opaque;
     qemuDomainObjPrivate *priv = dom->privateData;
+    virQEMUDriver *driver = priv->driver;
     virObjectEvent *event = NULL;
     unsigned int stopFlags = 0;