The aml/update_mainline_tags.sh script updates the vars/aml_tags file
to include the latest available mainline (APEX) module tags in its
modules_to_tags array, based on the keys present in the modules_to_apps
associative array of vars/aml.
Issue: calyxos#298
Change-Id: Ibcb5472a6a48d3d8317ec616ba521b18b407602f