vexpress64: Enable VIRTIO_NET network driver

The SMSC driver is using the old driver model.

Init the virtio system in vexpress64.c so that the network device is
discovered.

Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/board/armltd/vexpress64/vexpress64.c b/board/armltd/vexpress64/vexpress64.c
index d17b463..5e22e89 100644
--- a/board/armltd/vexpress64/vexpress64.c
+++ b/board/armltd/vexpress64/vexpress64.c
@@ -18,6 +18,10 @@
 #include <dm/platform_data/serial_pl01x.h>
 #include "pcie.h"
 #include <asm/armv8/mmu.h>
+#ifdef CONFIG_VIRTIO_NET
+#include <virtio_types.h>
+#include <virtio.h>
+#endif
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -64,6 +68,9 @@
 int board_init(void)
 {
 	vexpress64_pcie_init();
+#ifdef CONFIG_VIRTIO_NET
+	virtio_init();
+#endif
 	return 0;
 }