MAINTAINERS: add missing entries for virtio

Some head files were split or moved to uapi/ without
updating MAINTAINERS.
Signed-off-by: Amos Kong <kongjianjun@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

MAINTAINERS

@@ -8609,6 +8609,7 @@ F:	drivers/virtio/
 F:	drivers/net/virtio_net.c
 F:	drivers/block/virtio_blk.c
 F:	include/linux/virtio_*.h
+F:	include/uapi/linux/virtio_*.h
 
 VIRTIO HOST (VHOST)
 M:	"Michael S. Tsirkin" <mst@redhat.com>