Upgrade common-packer to v0.7.6

Signed-off-by: Vanessa Rene Valderrama <vvalderrama@linuxfoundation.org>
Change-Id: I8c358ae6a244db7c22adbb99d269f9c5748cb74f

diff --git a/packer/common-packer b/packer/common-packer
index 566435f..74b6be7 160000 (submodule)
--- a/packer/common-packer
+++ b/packer/common-packer
@@ -1 +1 @@
-Subproject commit 566435f6aa05f36336a56ec5819f658292fe30d4
+Subproject commit 74b6be7301b5c407d1ccf4cf6093b3b8cd308ad7