packaging: setup: Do not enable NFS on upgrade

Do not allow configuring an NFS ISO domain on upgrade.

Bug-Url: https://bugzilla.redhat.com/1056777
Change-Id: I10734f3debd5e3fb122707deb0cb8b354fbe2fa6
Signed-off-by: Yedidyah Bar David <didi@redhat.com>