cfg80211: fix refcount imbalance when wext is disabled

When CONFIG_CFG80211_WEXT is not set, there is
a refcount imbalance with rdev->opencount, fix
that by moving it out of the ifdef.

Reported-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>