mac80211: fix debugfs netdev rename

If, for some reason, a netdev has no debugfs dir, we shouldn't
try to rename that dir.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Robin Holt <holt@sgi.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
1 file changed