driver: Move x86_64 from ide to virtio

This allows booting up via EFI; without this, init panics because
/dev/sda is not found. The IDE block driver is seldom used, virtio is
better for our purposes.

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

Author: nathanchance

driver.sh

@@ -145,8 +145,8 @@ setup_variables() {
                          -initrd "images/x86_64/rootfs.cpio" ) ;;
         *)
           config=defconfig
-          qemu_cmdline=( -drive "file=images/x86_64/rootfs.ext4,format=raw,if=ide"
-                         -append "console=ttyS0 root=/dev/sda" ) ;;
+          qemu_cmdline=( -drive "file=images/x86_64/rootfs.ext4,format=raw,if=virtio"
+                         -append "console=ttyS0 root=/dev/vda" ) ;;
       esac
       # Use KVM if the processor supports it (first part) and the KVM module is loaded (second part)
       [[ $(grep -c -E 'vmx|svm' /proc/cpuinfo) -gt 0 && $(lsmod 2>/dev/null | grep -c kvm) -gt 0 ]] && qemu_cmdline=( "${qemu_cmdline[@]}" -enable-kvm )