configs/acmesystems_acqua_a5_{256, 512}mb: add openssl host dependency

The Linux build needs openssl:

https://gitlab.com/buildroot.org/buildroot/-/jobs/1240157423
https://gitlab.com/buildroot.org/buildroot/-/jobs/1240157424



Signed-off-by: Edgar Bonet <bonet@grenoble.cnrs.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>