[WIRELESS] cfg80211: Fix locking in wiphy_new.

This patch fixes the locking in wiphy new. Ingo Oeser
<netdev@axxeo.de> noticed that locking in the error case was wrong and
also suggested this fix.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>