Fix var passing

Change-Id: I01d1915b71e5ccbd7d65e96e2d149e5d89762a87
diff --git a/mirror-image/template.json b/mirror-image/template.json
index 711f7ed..6322511 100644
--- a/mirror-image/template.json
+++ b/mirror-image/template.json
@@ -56,7 +56,8 @@
         "APT_MIRANTIS_SALT_GPG={{ user `apt_mirantis_gpg` }}",
         "APT_MIRANTIS_SALT_REPO={{ user `apt_mirantis_salt_repo` }}",
         "GIT_SALT_FORMULAS_SCRIPTS={{ user `git_salt_formulas_scripts` }}",
-        "PACKER_OFFLINE_BUILD=true"
+        "PACKER_OFFLINE_BUILD=true",
+        "MCP_VERSION={{ user `mcp_version` }}"
       ],
       "type": "shell",
       "execute_command": "chmod +x {{ .Path }}; {{ .Vars }} {{ .Path }}",