angstrom-image: like systemd-image, but without connman

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
angstrom-image: get rid of double 'Angstrom'

DISTRO.conf already prepends 'Angstrom' automagically.

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>