salt.utils.network._interfaces_ifconfig: SunOS fix

In SunOS 11.1 with IPv6 enabled interfaces occur twice in 'ifconfig -a'
output with the same name: for ipv4 and then for ipv6 addr family. Thus,
ipv6 data overwrites data collected from ipv4 interfaces.

Every instance has it's own 'UP' status and we assume that ipv4
status determines global interface status.

Thus commit tries to merge data from conflicting instances.

Also, regexp was tuned for SunOS's ifconfig.
Lint fixes: unused import, tabs
Merge pull request #18592 from nazgul5/utils.network

salt.utils.network._interfaces_ifconfig: SunOS fix