staging/octeon: Software should check the checksum of no tcp/udp packets

staging/octeon: Software should check the checksum of no tcp/udp packets

Icmp packets with wrong checksum are never dropped since skb->ip_summed is
set to CHECKSUM_UNNECESSARY.

When icmp packets with wrong checksum pass through the octeon net driver,
the not_IP, IP_exc, L4_error hardware indicators show no error. so the
driver sets CHECKSUM_UNNECESSARY on skb->ip_summed.

L4_error only works for TCP/UDP, not for ICMP.

Signed-off-by: Roy.Li <rongqing.li@windriver.com>
To: linux-mips@linux-mips.org
Cc: netdev@vger.kernel.org
Cc: ralf@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2798/
Acked-by: David Daney <david.daney@cavium.com>
Cc: Greg KH <greg@kroah.com
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>