net: do not pretend FRAGLIST support

Few network drivers really supports frag_list : virtual drivers.

Some drivers wrongly advertise NETIF_F_FRAGLIST feature.

If skb with a frag_list is given to them, packet on the wire will be
corrupt.

Remove this flag, as core networking stack will make sure to
provide packets that can be sent without corruption.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Cc: Anirudha Sarangi <anirudh@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>