net: NETIF_F_HW_CSUM does not imply FCoE CRC offload

NETIF_F_HW_CSUM indicates the ability to update an TCP/IP-style 16-bit
checksum with the checksum of an arbitrary part of the packet data,
whereas the FCoE CRC is something entirely different.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Cc: stable@kernel.org [2.6.32+]
Signed-off-by: David S. Miller <davem@davemloft.net>