dracut: rewrite ip checks to be more stable

remove simple ip_ifname check, as there are ip(4|6)_forever and wait_for_ip(4|6)_renew.

nmcli_con_active is dynamically waiting until connection gets activated (--active switch is not enough, as connection is active even while it is getting the lease). Also, make this before the IP checks, to be sure that IP is assigned.