LU-11838: lnet: remove lnet_ipif_enumerate()

LU-11838: lnet: remove lnet_ipif_enumerate()

Also remove lnet_ipif_query() and related functions.

There are no longer any users of these functions, so remove them.

Linux-commit: 6e659fcfab0cdd876a555a752acf9997f98acbcd

This patch is back-ported from the following one:
Lustre-commit: dedd3706945ef759d7d645cde30fa488c8ced4a1
Lustre-change: https://review.whamcloud.com/34234

Change-Id: I8183e505e3dbe12ff71ddf38f5b18a945d8a4a6c
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Reviewed-by: Petros Koutoupis <pkoutoupis@cray.com>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-by: Aurelien Degremont <degremoa@amazon.com>
Reviewed-on: https://review.whamcloud.com/35160
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>