net: usb: asix: ax88772: Fix less than zero comparison of a u16

The comparison of the u16 priv->phy_addr < 0 is always false because
phy_addr is unsigned. Fix this by assigning the return from the call
to function asix_read_phy_addr to int ret and using this for the
less than zero error check comparison.

Fixes: 7e88b11a ("net: usb: asix: refactor asix_read_phy_addr() and handle errors on return")
Addresses-Coverity: ("Unsigned compared against 0")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/usb/ax88172a.c

@@ -205,11 +205,11 @@ static int ax88172a_bind(struct usbnet *dev, struct usb_interface *intf)
 		goto free;
 	}
 
-	priv->phy_addr = asix_read_phy_addr(dev, priv->use_embdphy);
-	if (priv->phy_addr < 0) {
-		ret = priv->phy_addr;
+	ret = asix_read_phy_addr(dev, priv->use_embdphy);
+	if (ret < 0)
 		goto free;
-	}
+
+	priv->phy_addr = ret;
 
 	ax88172a_reset_phy(dev, priv->use_embdphy);