ppc: qemu: Enable VirtIO BLK support

Enable VirtIO BLK driver so that we can store a kernel image to
a disk image and boot from there.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/configs/qemu-ppce500_defconfig b/configs/qemu-ppce500_defconfig
index 202e97e..b2510c8 100644
--- a/configs/qemu-ppce500_defconfig
+++ b/configs/qemu-ppce500_defconfig
@@ -26,6 +26,8 @@
 CONFIG_ENV_OVERWRITE=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_DM=y
+CONFIG_BLK=y
+CONFIG_HAVE_BLOCK_DEVICE=y
 # CONFIG_MMC is not set
 CONFIG_DM_ETH=y
 CONFIG_E1000=y
@@ -35,5 +37,6 @@
 CONFIG_SYS_NS16550=y
 CONFIG_VIRTIO_PCI=y
 CONFIG_VIRTIO_NET=y
+CONFIG_VIRTIO_BLK=y
 CONFIG_ADDR_MAP=y
 CONFIG_PANIC_HANG=y