LU-11838 socklnd: use for_each_netdev() instead of lnet_ipif_enumerate()

LU-11838 socklnd:  use for_each_netdev() instead of lnet_ipif_enumerate()

for_each_netdev() is a more direct interface and doesn't require
library support.

Also get the ip address directly from the net_device, rather than
using lnet_ipif_query().

Linux-commit: f703f71afd98e6e7ec70f92ffc52ef3ffffcd849
Linux-commit: 9eb957b98aa6322abde33240bf50dd483c5d1190

This patch is back-ported from the following one:
Lustre-commit: e9d9cbb072956f2582c97263184aecd196bba14a
Lustre-change: https://review.whamcloud.com/33966

Change-Id: I82894991b9a4a250d0560af31325b6c765cc0620
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Sonia Sharma <sharmaso@whamcloud.com>
Reviewed-by: Doug Oucharek <dougso@me.com>
Reviewed-on: https://review.whamcloud.com/35158
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>