images: also allow extended images to build without kvm

Removes the -cpu host parameter to qemu which only works with kvm.

images/extended-image.pkr.hcl

@@ -35,8 +35,7 @@ source "qemu" "autogenerated_1" {
   memory           = "${var.memory}"
   net_device       = "virtio-net"
   output_directory = "output-${var.outname}"
-  qemuargs         = [["-machine", "pc-q35-4.2,accel=kvm:tcg,usb=off,vmport=off,dump-guest-core=off"],
-                      ["-cpu", "host"]]
+  qemuargs         = [["-machine", "pc-q35-4.2,accel=kvm:tcg,usb=off,vmport=off,dump-guest-core=off"]]
   shutdown_command = "sudo shutdown --poweroff --no-wall now"
   ssh_password     = "ubuntu"
   ssh_username     = "ubuntu"