ca install: merge duplicated code for DM password
Extract copy-pasted code to a single function.
Related https://pagure.io/freeipa/issue/6892
Signed-off-by: Tomas Krizek <tkrizek@redhat.com>
Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>