LU-13641 socklnd: remove remnants of tcp bonding

LU-13641 socklnd: remove remnants of tcp bonding

->ksnp_n_passive_ips is now always zero, so remove it and all uses of
it.  ->ksnp_passive_ips is gone too, as is ksocknal_ip2iface().

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I5de6d027c545087c961673d8704f68c4f3dd5076
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/48568
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>