CI: Update common packer to latest v0.12.1

Signed-off-by: Anil Belur <abelur@linuxfoundation.org>
Change-Id: I3f97794945c12d24c78251c5cf3b6621f4b8b898

diff --git a/packer/common-packer b/packer/common-packer
index b8bffd6..15aba27 160000 (submodule)
--- a/packer/common-packer
+++ b/packer/common-packer
@@ -1 +1 @@
-Subproject commit b8bffd625cbf589079fcfd9ba1a37c91fdc7f99b
+Subproject commit 15aba27a45f98edb33890daa3712c6a4371b2947