This is the continuation of the ifconfig cleanup work. This change is a pre-requsite for the next changes removing some of the global variables. It will also help in implementing functionality via Netlink instead of ioctl.
No functional changes intended.
* vxlan_cb() was removed as it contained no code
* ioctl_ifcreate() was renamed to ifcreate_ioctl() to follow the other netlink/ioctl function naming. Netlink and ioctl provide _different_ interfaces and it's not possible to have a unified interface object that can be filled by either netlink or ioctl implementations. With that in mind, I'm leaning more to the function_<nl|ioctl> postfix pattern, than doing ioctl_ or netlink_ prefix.