findif.sh: fix loopback handling

[vvidic]

tools/ocft/IPaddr2 fails the loopback test because of the missing table local parameter:

$ ip -o -f inet route list match 127.0.0.3 scope host

$ ip -o -f inet route list match 127.0.0.3 table local scope host
local 127.0.0.0/8 dev lo proto kernel src 127.0.0.1

Also rename the function because it is called only in for the special loopback address case.

[knet-jenkins[bot]]

Can one of the admins check and authorise this run please: https://ci.kronosnet.org/job/resource-agents/job/resource-agents-pipeline/job/PR-1898/1/input

[oalbrigt]

Thanks.