cx82310_eth: check usb_string() return value for error

Fix that usb_string() return value is not checked for error (negative value).
Also change the ignore message a bit and lower its level to info.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/usb/cx82310_eth.c b/drivers/net/usb/cx82310_eth.c
index 6fbe032..4d45178 100644
--- a/drivers/net/usb/cx82310_eth.c
+++ b/drivers/net/usb/cx82310_eth.c
@@ -138,11 +138,9 @@
 	struct usb_device *udev = dev->udev;
 
 	/* avoid ADSL modems - continue only if iProduct is "USB NET CARD" */
-	if (udev->descriptor.iProduct &&
-	    usb_string(udev, udev->descriptor.iProduct, buf, sizeof(buf)) &&
-	    strcmp(buf, "USB NET CARD")) {
-		dev_err(&udev->dev,
-			"probably an ADSL modem, use cxacru driver instead\n");
+	if (usb_string(udev, udev->descriptor.iProduct, buf, sizeof(buf)) > 0
+	    && strcmp(buf, "USB NET CARD")) {
+		dev_info(&udev->dev, "ignoring: probably an ADSL modem\n");
 		return -ENODEV;
 	}