virtio: Add net driver support

This adds virtio net device driver support.

Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 4f9a11b..e20dd69 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -29,4 +29,11 @@
 	  This driver provides support for memory mapped virtio
 	  platform device driver.
 
+config VIRTIO_NET
+	bool "virtio net driver"
+	depends on VIRTIO
+	help
+	  This is the virtual net driver for virtio. It can be used with
+	  QEMU based targets.
+
 endmenu