staging: r8712u: fix potential NULL pointer dereference in r871x_wps_start()

The dereference should be moved below the NULL test.

dpatch engine is used to auto generate this patch.
(https://github.com/weiyj/dpatch)
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8712/rtl871x_ioctl_linux.c

@@ -2110,10 +2110,10 @@ static int r871x_wps_start(struct net_device *dev,
 	struct iw_point *pdata = &wrqu->data;
 	u32   u32wps_start = 0;
 
-	if (copy_from_user((void *)&u32wps_start, pdata->pointer, 4))
-		return -EFAULT;
 	if ((padapter->bDriverStopped) || (pdata == NULL))
 		return -EINVAL;
+	if (copy_from_user((void *)&u32wps_start, pdata->pointer, 4))
+		return -EFAULT;
 	if (u32wps_start == 0)
 		u32wps_start = *extra;
 	if (u32wps_start == 1) /* WPS Start */