lvm2: update to 2.02.107

Newer ebuilds appear to fix some issues with systemd integration which
may or may not impact our systems but lvm isn't widely used with CoreOS
so no one has noticed. Most importantly though these sorts of errors are
gone:

    Configuration file /run/systemd/generator/lvm2-activation.service is
    marked world-inaccessible. This has no effect as configuration data
    is accessible via APIs without restrictions. Proceeding anyway.

Depends on https://github.com/coreos/portage-stable/pull/124