[review] dcbw/ipv6-fixes: fix IPv6 support in core and plugins

[Thomas Schäfer]

Same test with K5150 (mbim) looks not so nice:

What means gateway: '::' ?

Does the nm use this information? Is there a other command to show the ip-
config via mmcli?




mmcli -b 1

Bearer '/org/freedesktop/ModemManager1/Bearer/1'
  -------------------------
  Status             |   connected: 'yes'
                     |   suspended: 'no'
                     |   interface: 'wwan0'
                     |  IP timeout: '20'
  -------------------------
  Properties         |         apn: 'fourier52.testnetz-vd2.de'
                     |     roaming: 'allowed'
                     |     IP type: 'ipv4v6'
                     |        user: 'none'
                     |    password: 'none'
                     |      number: 'none'
                     | Rm protocol: 'unknown'
  -------------------------
  IPv4 configuration |   method: 'dhcp'
                     |  address: 'unknown'
                     |   prefix: '0'
                     |  gateway: 'unknown'
                     |      DNS: none
  -------------------------
  IPv6 configuration |   method: 'static'
                     |  address: '2a01:198:24c:c175:5a2c:80ff:fe13:9208'
                     |   prefix: '64'
                     |  gateway: '::'
                     |      DNS: '2a01:198:24c:d000::5', '::'
                     |      MTU: '1500'