rsi: Fix a potential memory leak in rsi_send_auto_rate_request()

Fix a potential memory leak in the error path of function
rsi_send_auto_rate_request(). In case memory allocation for array
'selected_rates' fails, the error path exits and leaves the previously
allocated skb in place. Detected by Coverity: CID 1195575.
Signed-off-by: Christian Engelmayer <cengelma@gmx.at>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rsi/rsi_91x_mgmt.c

@@ -966,6 +966,7 @@ static int rsi_send_auto_rate_request(struct rsi_common *common)
 	if (!selected_rates) {
 		rsi_dbg(ERR_ZONE, "%s: Failed in allocation of mem\n",
 			__func__);
+		dev_kfree_skb(skb);
 		return -ENOMEM;
 	}