staging: wlan-ng: Fix dereference before NULL check

Smatch is warning about a dereference before we check for NULL.
This patch moves the dereference to after the NULL check.

Smatch warning:
drivers/staging/wlan-ng/cfg80211.c:345 prism2_scan() warn:
	variable dereferenced before check 'request' (see line 332)
Signed-off-by: NEmil Goode <emilgoode@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wlan-ng/cfg80211.c

@@ -329,9 +329,9 @@ int prism2_get_station(struct wiphy *wiphy, struct net_device *dev,
 
 int prism2_scan(struct wiphy *wiphy, struct cfg80211_scan_request *request)
 {
-	struct net_device *dev = request->wdev->netdev;
+	struct net_device *dev;
 	struct prism2_wiphy_private *priv = wiphy_priv(wiphy);
-	wlandevice_t *wlandev = dev->ml_priv;
+	wlandevice_t *wlandev;
 	struct p80211msg_dot11req_scan msg1;
 	struct p80211msg_dot11req_scan_results msg2;
 	struct cfg80211_bss *bss;
@@ -345,6 +345,9 @@ int prism2_scan(struct wiphy *wiphy, struct cfg80211_scan_request *request)
 	if (!request)
 		return -EINVAL;
 
+	dev = request->wdev->netdev;
+	wlandev = dev->ml_priv;
+
 	if (priv->scan_request && priv->scan_request != request)
 		return -EBUSY;