gpio: virtio: reorder fields to reduce struct padding

Reorder struct virtio_gpio_line fields to place the DMA buffers
(req/res) last.

This eliminates the padding from aligning struct size on
ARCH_DMA_MINALIGN.

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Message-ID: <f1221bbc120df6adaba9006710a517f1e84a10b2.1767601130.git.mst@redhat.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Author: mstsirkin

drivers/gpio/gpio-virtio.c

@@ -26,11 +26,12 @@ struct virtio_gpio_line {
 	struct mutex lock; /* Protects line operation */
 	struct completion completion;
 
+	unsigned int rxlen;
+
 	__dma_from_device_group_begin();
 	struct virtio_gpio_request req;
 	struct virtio_gpio_response res;
 	__dma_from_device_group_end();
-	unsigned int rxlen;
 };
 
 struct vgpio_irq_line {