nl80211: fix missing nesting

commit 95a6ccbb46c70cff376684c752831c014c87029d
Author: Johannes Berg <johannes.berg@intel.com>
Date:   Thu Aug 12 15:38:38 2010 +0200

    cfg80211/mac80211: extensible frame processing

introduced a netlink bug that caused parsing errors
in userspace because it forgot to close a nesting,
which would advertise a nesting length of zero to
userspace, which then completely threw off parsing
and led to

	Illegal nla->nla_type == 0

being printed by libnl.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>