Fix to return -EPROTO error if fragments detected in checksum_setup_ip().
Fixes: 1431fb31ecba ('xen-netback: fix fragment detection in checksum setup') Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Reviewed-by: Paul Durrant <paul.durrant@citrix.com> Acked-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: David S. Miller <davem@davemloft.net>