resume: Also allow this module on S390 again -> s2disk can work on s390(x)

bnc#889795

Signed-off-by: Thomas Renninger <trenn@suse.de>
iscsi: iscsi.initiator and others can and must only show up once

Make sure duplicates of iscsi.initiator vanish.
Only get one rd.iscsi.* paramter value. If getargs is used and several
parameters are parsed, one gets two values separated by whitespace in a
variable which breaks later code and is not suppported.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Merge branch 'sles12' of https://github.com/hreinecke/dracut into sles12