LU-17914 lnet: Fix erroneous net set error

LU-17914 lnet: Fix erroneous net set error

lnetctl net set --health command reports a false error. This is
because in lnet_genl_parse_local_ni() the last value stored in rc is
from nla_strscpy() which can return a positive value.

Test-Parameters: trivial testlist=sanity-lnet
Fixes: fff650726b ("LU-13642 lnet: Allow dynamic IP specification")
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: I86211a1083af4b225076f966d2e0c7793589a33a
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55344
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>