wireless: display wext SSID when connected by cfg80211

cfg80211 displays correct link info when connected by wext. But if
the connection is setup by cfg80211, wext cannot display the SSID.
This patch fixed this issue.

Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>