Enable systemd-resolved
    
    Technically this doesn't change anything because 90-systemd.preset also
    enables this, but let's add an explicit 'enable' here to make it clear that
    this is on purpose, and not just an ommission.
    
    Follow-up for f0ded50a1e532fbac26f7f38f7898daf2cf5dab8.
    
    Signed-off-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>