LU-12634 lnet: for_ifa removed. Use in_dev_for_each_ifa_rtnl

LU-12634 lnet: for_ifa removed. Use in_dev_for_each_ifa_rtnl

Linux 5.3 removed for_ifa and replaced it with an _rntl and _rcu
versions for use with their respective locking primitives.

kernel-commit: ef11db3310e272d3d8dbe8739e0770820dd20e52

This patch is back-ported from the following one:
Lustre-commit: 6e0d0146276353559c821916e193c90d167b14e0
Lustre-change: https://review.whamcloud.com/35744

Test-Parameters: trivial
Cray-bug-id: LUS-7689
Signed-off-by: Shaun Tancheff <stancheff@cray.com>
Change-Id: Iea07222b9abb3f9c219d28fe2c660d9eaf21af80
Reviewed-on: https://review.whamcloud.com/38487
Reviewed-by: Petros Koutoupis <petros.koutoupis@hpe.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>