driver: Fix arm64's qemu_cmdline to specify virtio-blk-device

We need this to support booting up with EFI, otherwise arm64 on 4.4
panics because the block device cannot be found. This mirrors what is
done for arm32.

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

Author: nathanchance

driver.sh

@@ -85,7 +85,8 @@ setup_variables() {
       image_name=Image.gz
       qemu="qemu-system-aarch64"
       qemu_cmdline=( -cpu cortex-a57
-                     -drive "file=images/arm64/rootfs.ext4,format=raw"
+                     -drive "file=images/arm64/rootfs.ext4,format=raw,id=rootfs,if=none"
+                     -device "virtio-blk-device,drive=rootfs"
                      -append "console=ttyAMA0 root=/dev/vda" )
       export CROSS_COMPILE=aarch64-linux-gnu- ;;