cx82310_eth: fix error return code in cx82310_bind()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: ca139d76b0d9 ("cx82310_eth: re-enable ethernet mode after router reboot")
Reported-by: Hulk Robot <[e-mail]>
Signed-off-by: Zhang Changzhong <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/usb/cx82310_eth.c

···
 	}
 
 	/* enable ethernet mode (?) */
-	if (cx82310_enable_ethernet(dev))
+	ret = cx82310_enable_ethernet(dev);
+	if (ret)
 		goto err;
 
 	/* get the MAC address */