fix #3677: follow up: actually handle bucket size and ignore initval

fix #3677: follow up: actually handle bucket size and ignore initval

The former is simply new and we can control it, so do so instead of
ignoring it, if it seems worth while we can also expose that as
option or do some fancier auto calculation, maybe depending on ipset
size.

The u32 `initval` is a bit different, its not a config in the exact
traditional sense but would allow to recreate an bit to bit
indentical save/restore - but we do not really do that and we cannot
pre-calculate that our self (or at least I'd rather like to avoid
doing that from perl).. So, ignore it actively for now to avoid
false-postivie detection in pending changes.

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