virtio_gpu: correct tags for config space fields

Since gpu is a modern-only device,
tag config space fields as having little endian-ness.

Signed-off-by: Michael S. Tsirkin <[e-mail]>
Reviewed-by: Cornelia Huck <[e-mail]>

include/uapi/linux/virtio_gpu.h

···
 #define VIRTIO_GPU_EVENT_DISPLAY (1 << 0)
 
 struct virtio_gpu_config {
-	__u32 events_read;
-	__u32 events_clear;
-	__u32 num_scanouts;
-	__u32 num_capsets;
+	__le32 events_read;
+	__le32 events_clear;
+	__le32 num_scanouts;
+	__le32 num_capsets;
 };
 
 /* simple formats for fbcon/X use */