LU-14742 socklnd: detect link state to set fatal error on ni

LU-14742 socklnd: detect link state to set fatal error on ni

To help avoid selecting lnet ni which corresponds to a downed
ethernet link for sending, add a mechanism for detecting link
events in socklnd. On link up/down events, find corresponding
ni and toggle ni_fatal_error_on flag, similar to o2iblnd way.

Lustre-change: https://review.whamcloud.com/43952
Lustre-commit: fc2df80e96dc5db9f3fb710893ccf6f442664471

Test-Parameters: trivial
Signed-off-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Change-Id: Ie9f4f02fcb8b988c77bf63f751d5a621e79e9f58
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/44329
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>