added architecture to saltstack repo

Change-Id: I21b8aa2fbf1c73fe88db0ed41ea95de18b8e18dd
diff --git a/linux/system/repo/saltstack/xenial.yml b/linux/system/repo/saltstack/xenial.yml
index 0c933b8..aca462a 100644
--- a/linux/system/repo/saltstack/xenial.yml
+++ b/linux/system/repo/saltstack/xenial.yml
@@ -6,4 +6,5 @@
       repo:
         salt:
           source: "deb http://repo.saltstack.com/apt/ubuntu/16.04/amd64/${_param:salt_version} xenial main"
+          architectures: amd64
           key_url: "http://repo.saltstack.com/apt/ubuntu/16.04/amd64/${_param:salt_version}/SALTSTACK-GPG-KEY.pub"
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