Combined L3+L4 csum offload is only required for some L3 HW. So for
L2 devices, don't offload the IP header csum calculation.
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Reference-ID: JUP 394553
Signed-off-by: NDavid S. Miller <davem@davemloft.net>