fix #862: do not resolve portal adress on storage add

fix #862: do not resolve portal adress on storage add

as described in #862:

> I experienced a problem with ISCSI portal when using a hostname and
> not IP.
> The GUI resolves the hostname to an IP and writes it to storage.cfg.
> As my setup requires hostnames, i needed to change the config
> manually back to the hostname which is working fine.
>
> Why is this conversion done? If I enter a hostname, i want to have a
> hostname. If i enter an IP address i want to have an IP address.

This makes sense to me, a feature of using domains is that they
are/should be resolved when actually using (i.e., connecting to them)
so resolving it once on add does not seems like a good idea (if I do
not miss something - as this is a classic "imported from SVN" I do
not have any rationale to look at).

So save the work and pass it as is.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>