netns: define extack error msg for nsis cmds

It helps the user to identify errors.

CC: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Nicolas Dichtel 2017-06-09 14:41:56 +02:00 • committed by David S. Miller
commit 4a7f7bc600