debian: Rename abi directory to current endless release

With the previous hack to keep the two changelogs in sync, the debian
packaging will now regard the version OBS generates correctly. That
means that when OBS is running, the previous version will be endlessX
and the current version will be endlessXbemY.

In that case, we need to change the module ABI directory name (or add a
new module directory) every time we do a release so that the the ABI
checker will find the "previous" version file.

[endlessm/eos-shell#2600]