net: dsa: lan9303: Fix error return code in lan9303_check_device()

Fix to return error code -ENODEV from the chip not found error handling
case instead of 0(ret have been overwritten to 0 by lan9303_read()), as
done elsewhere in this function.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Egil Hjelmeland <privat@egil-hjelmeland.no>
Signed-off-by: David S. Miller <davem@davemloft.net>