Fix input device update

[futuretea]

Related issues
harvester/harvester#3336

Problem
The input device cannot be removed normally

Test plan

1. create a vm with an input device

resource "harvester_image" "ubuntu20" {
  name      = "ubuntu20"
  namespace = "harvester-public"

  display_name = "ubuntu-20.04-server-cloudimg-amd64.img"
  source_type  = "download"
  url          = "http://cloud-images.ubuntu.com/releases/focal/release/ubuntu-20.04-server-cloudimg-amd64.img"
}

resource "harvester_virtualmachine" "ubuntu20" {
  name                 = "ubuntu20"
  namespace            = "default"
  restart_after_update = true

  description = "test ubuntu20 raw image"
  tags = {
    ssh-user = "ubuntu"
  }

  cpu    = 2
  memory = "2Gi"

  efi         = true
  secure_boot = true

  run_strategy    = "RerunOnFailure"
  hostname        = "ubuntu20"
  reserved_memory = "100Mi"
  machine_type    = "q35"

  network_interface {
    name           = "nic-1"
    wait_for_lease = true
  }

  disk {
    name       = "rootdisk"
    type       = "disk"
    size       = "10Gi"
    bus        = "virtio"
    boot_order = 1

    image       = harvester_image.ubuntu20.id
    auto_delete = true
  }

  disk {
    name        = "emptydisk"
    type        = "disk"
    size        = "20Gi"
    bus         = "virtio"
    auto_delete = true
  }

  cloudinit {
    user_data    = <<-EOF
      #cloud-config
      password: 123456
      chpasswd:
        expire: false
      ssh_pwauth: true
      package_update: true
      packages:
        - qemu-guest-agent
      runcmd:
        - - systemctl
          - enable
          - '--now'
          - qemu-guest-agent
      EOF
    network_data = ""
  }
  input {
    name = "tablet"
    type = "tablet"
    bus  = "usb"
  }
}

terraform apply

2. remove the input field

vim main.tf

terraform apply

[chrisho]

LGTM,thanks.

[guangbochen]

LGTM, thanks.