net: calxedaxgmac: remove NETIF_F_FRAGLIST setting

The xgmac does not actually handle frag lists, so this option should not
be set. It does not appear to have had any impact though.

Reported-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: David S. Miller <davem@davemloft.net>