Allow multiple declarations of ARM64 of HWE kernel package

The openafs puppet module also declares a linux-generic-hwe-16.04
package for arm64 as it is required for those modules.  This is to
cover the non-afs server case, where the later kernel still works
better anyway.  Switch to ensure_packages, which handles if it is
already declared, so everyone can live together in peace.

Change-Id: I72c9423956b7739695a04a5de27f5d89c67240d0

modules/openstack_project/manifests/server.pp

@@ -344,9 +344,7 @@ class openstack_project::server (
   if ($::lsbdistcodename == 'xenial' and $::architecture == 'aarch64') {
     # Make sure we install the HWE kernel for arm64; it's 4.13 v 4.3
     # and works much better on linaro cloud
-    package { 'linux-generic-hwe-16.04':
-      ensure => present,
-    }
+    ensure_packages(['linux-generic-hwe-16.04'])
   }
 
 }