40network: Update iBFT scanning code to handle IPv6

IPv6 addresses should be specified in brackets so that the
ip= scanning code doesn't get confused.

References: bnc#887542

Signed-off-by: Hannes Reinecke <hare@suse.de>
40network: separate 'mask' and 'prefix'

The 'mask' parameter is used for both, the (IPv4) netmask and
the prefix length. As both are in different format separate them
out into 'mask' for the netmask and 'prefix' for the prefix length.
And also prefer the use of 'prefix' where possible to ease
calculation and better IPv6 support.

References: bnc#887542

Signed-off-by: Hannes Reinecke <hare@suse.de>