rsi: Fixed issue relating to variable de-referenced before check 'adapter'

Signed-off-by: NFariya Fatima <fariyaf@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rsi/rsi_91x_sdio.c

@@ -756,12 +756,13 @@ static int rsi_probe(struct sdio_func *pfunction,
 static void rsi_disconnect(struct sdio_func *pfunction)
 {
 	struct rsi_hw *adapter = sdio_get_drvdata(pfunction);
-	struct rsi_91x_sdiodev *dev =
-		(struct rsi_91x_sdiodev *)adapter->rsi_dev;
+	struct rsi_91x_sdiodev *dev;
 
 	if (!adapter)
 		return;
 
+	dev = (struct rsi_91x_sdiodev *)adapter->rsi_dev;
+
 	dev->write_fail = 2;
 	rsi_mac80211_detach(adapter);