RDMA/siw: Remove namespace check from siw_netdev_event()

RDMA/siw: Remove namespace check from siw_netdev_event()

[ Upstream commit 266e9b3475ba82212062771fdbc40be0e3c06ec8 ]

syzbot is reporting that siw_netdev_event(NETDEV_UNREGISTER) cannot destroy
siw_device created after unshare(CLONE_NEWNET) due to net namespace check.
It seems that this check was by error there and should be removed.

Reported-by: syzbot <syzbot+5e70d01ee8985ae62a3b@syzkaller.appspotmail.com>
Link: https://syzkaller.appspot.com/bug?extid=5e70d01ee8985ae62a3b
Suggested-by: Jason Gunthorpe <jgg@ziepe.ca>
Suggested-by: Leon Romanovsky <leon@kernel.org>
Fixes: bdcf26bf9b3a ("rdma/siw: network and RDMA core interface")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/a44e9ac5-44e2-d575-9e30-02483cc7ffd1@I-love.SAKURA.ne.jp
Reviewed-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>