qdev: Complete qdev_init_gpio_out() documentation

qdev_init_gpio_out() states it "creates an array of anonymous
output GPIO lines" but doesn't document how this array is
released. Add a note that it is automatically free'd in qdev
instance_finalize().

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20210819142731.2827912-1-philmd@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

include/hw/qdev-core.h

@@ -598,6 +598,10 @@ void qdev_init_gpio_in(DeviceState *dev, qemu_irq_handler handler, int n);
  *
  * See qdev_connect_gpio_out() for how code that uses such a device
  * can connect to one of its output GPIO lines.
+ *
+ * There is no need to release the @pins allocated array because it
+ * will be automatically released when @dev calls its instance_finalize()
+ * handler.
  */
 void qdev_init_gpio_out(DeviceState *dev, qemu_irq *pins, int n);
 /**