Fix problem when using hcl2 for packer templates.

[fr123k]

The error message was unknown configuration key "download_path" and
unknown configuration key "skip_install".

[Lirt]

Hello, what is the state with this bug? I encountered it today with latest packer v1.6.5 HCL2 on Linux.

[Lirt]

cc. @EleanorRigby even when I use empty block like this:

  provisioner "goss" {
  }

I end up with error like this:

Error: Failed preparing provisioner-block "goss" ""

  on default.pkr.hcl line 98:
  (source code not available)

2 errors occurred:
	* unknown configuration key: "download_path"; raws is []interface
{}{map[string]interface {}{"packer_build_name":"ubuntu-18-04",
"packer_builder_type":"openstack"}, map[string]interface {}{"arch":interface
{}(nil), "download_path":interface {}(nil), "format":interface {}(nil),
"format_options":interface {}(nil), "goss_file":interface {}(nil),
"inspect":interface {}(nil), "password":interface {}(nil),
"remote_folder":interface {}(nil), "remote_path":interface {}(nil),
"retry_timeout":interface {}(nil), "skip_install":interface {}(nil),
"skip_ssl":interface {}(nil), "sleep":interface {}(nil), "tests":interface
{}(nil), "url":interface {}(nil), "use_sudo":interface {}(nil),
"username":interface {}(nil), "vars_env":interface {}(nil),
"vars_file":interface {}(nil), "vars_inline":interface {}(nil),
"version":interface {}(nil)}, map[string]interface {}(nil)} 

 and ctx data is map[interface {}]interface {}(nil)
	* unknown configuration key: "skip_install"; raws is []interface
{}{map[string]interface {}{"packer_build_name":"ubuntu-18-04",
"packer_builder_type":"openstack"}, map[string]interface {}{"arch":interface
{}(nil), "download_path":interface {}(nil), "format":interface {}(nil),
"format_options":interface {}(nil), "goss_file":interface {}(nil),
"inspect":interface {}(nil), "password":interface {}(nil),
"remote_folder":interface {}(nil), "remote_path":interface {}(nil),
"retry_timeout":interface {}(nil), "skip_install":interface {}(nil),
"skip_ssl":interface {}(nil), "sleep":interface {}(nil), "tests":interface
{}(nil), "url":interface {}(nil), "use_sudo":interface {}(nil),
"username":interface {}(nil), "vars_env":interface {}(nil),
"vars_file":interface {}(nil), "vars_inline":interface {}(nil),
"version":interface {}(nil)}, map[string]interface {}(nil)} 

 and ctx data is map[interface {}]interface {}(nil)

[fishnix]

@fr123k it looks like this is included in a PR to update to the latest sdk PR #43 so I'm going to take those together and close this. Thanks for the PR!