added pinning for mcp repos, mk-apt and contrail

Change-Id: I3ca753e11290df0cf0727b3d8cbb18b2324c6f86
diff --git a/linux/system/repo/mcp/contrail.yml b/linux/system/repo/mcp/contrail.yml
index 9f65ee3..9054f18 100644
--- a/linux/system/repo/mcp/contrail.yml
+++ b/linux/system/repo/mcp/contrail.yml
@@ -9,3 +9,7 @@
           source: "deb [arch=amd64] http://apt-mk.mirantis.com/${_param:linux_system_codename}/ ${_param:apt_mk_version} ${_param:openstack_version} ${_param:linux_repo_contrail_component} extra"
           architectures: amd64
           key_url: "http://apt-mk.mirantis.com/public.gpg"
+          pin:
+          - pin: 'release a=${_param:openstack_version}-holdback'
+            priority: 1100
+            package: '*'
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