cleanup: fix export NIC count the same way as disk
cleanup: fix export NIC count the same way as disk

For safety, we use the same algorithm as in disk count.

Reviewed-by: amishchenko

apyrgio/ganeti,mbakke/ganeti,dimara/ganeti,andir/ganeti,leshchevds/ganeti,yiannist/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,onponomarev/ganeti,ganeti/ganeti,leshchevds/ganeti,leshchevds/ganeti,grnet/snf-ganeti,ganeti/ganeti,bitemyapp/ganeti,onponomarev/ganeti,ganeti-github-testing/ganeti-test-1,apyrgio/snf-ganeti,apyrgio/ganeti,apyrgio/snf-ganeti,mbakke/ganeti,ganeti/ganeti,mbakke/ganeti,andir/ganeti,bitemyapp/ganeti,andir/ganeti,dimara/ganeti,grnet/snf-ganeti,yiannist/ganeti