fix incorrect default value for dns_prefix_private_cluster

Author: lonegunmanb

main.tf

@@ -22,7 +22,7 @@ resource "azurerm_kubernetes_cluster" "main" {
   azure_policy_enabled                = var.azure_policy_enabled
   disk_encryption_set_id              = var.disk_encryption_set_id
   dns_prefix                          = var.private_cluster_enabled == true ? null : var.prefix
-  dns_prefix_private_cluster          = var.private_cluster_enabled == true ? var.prefix : false
+  dns_prefix_private_cluster          = var.private_cluster_enabled == true ? var.prefix : null
   image_cleaner_enabled               = var.image_cleaner_enabled
   image_cleaner_interval_hours        = var.image_cleaner_interval_hours
   kubernetes_version                  = var.kubernetes_version