riscv: qemu: Enumerate virtio bus during early boot

Currently devices on the virtio bus is not automatically enumerated,
which means peripherals on the virtio bus are not discovered by their
drivers. This uses board_init() to do the virtio enumeration.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/board/emulation/qemu-riscv/qemu-riscv.c b/board/emulation/qemu-riscv/qemu-riscv.c
index 041e716..2730a28 100644
--- a/board/emulation/qemu-riscv/qemu-riscv.c
+++ b/board/emulation/qemu-riscv/qemu-riscv.c
@@ -4,12 +4,21 @@
  */
 
 #include <common.h>
+#include <dm.h>
 #include <fdtdec.h>
+#include <virtio_types.h>
+#include <virtio.h>
 
 #define MROM_FDT_ADDR	0x1020
 
 int board_init(void)
 {
+	/*
+	 * Make sure virtio bus is enumerated so that peripherals
+	 * on the virtio bus can be discovered by their drivers
+	 */
+	virtio_init();
+
 	return 0;
 }