x86: qemu: Imply virtio PCI transport and device drivers

Add virtio drivers for QEMU x86 targets.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/board/emulation/qemu-x86/Kconfig b/board/emulation/qemu-x86/Kconfig
index 41a27dd..6d19299 100644
--- a/board/emulation/qemu-x86/Kconfig
+++ b/board/emulation/qemu-x86/Kconfig
@@ -21,5 +21,8 @@
 	select X86_RESET_VECTOR
 	select QEMU
 	select BOARD_ROMSIZE_KB_1024
+	imply VIRTIO_PCI
+	imply VIRTIO_NET
+	imply VIRTIO_BLK
 
 endif