LU-16606 lnet: lnet_parse_route uses wrong loop var

LU-16606 lnet: lnet_parse_route uses wrong loop var

When looping over the gateways list, we're referencing the wrong
loop variable to get the gateway nid (ltb instead of ltb2).

Test-Parameters: trivial testlist=sanity-lnet
Fixes: 3b76020810 ("LU-6142 lnet: use list_first_entry() in lnet/lnet subdirectory.")
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: Idbcc5e211fc8fd49831ba572805b60be511d0ffd
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50173
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: jsimmons <jsimmons@infradead.org>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>