qlge: remove NETIF_F_TSO6 flag

It is werid that qlge driver supports NETIF_F_TSO6 but
not NETIF_F_IPV6_CSUM. This also causes some kernel warning [1]
when VLAN device setups on a qlge interface.

I think the qlge hardware doesn't support NETIF_F_IPV6_CSUM,
so we have to just remove the NETIF_F_TSO6 flag.

After this patch, the TCP/IPv6 traffic becomes normal again,
no kernel warnings any more.

NOTE: I only tested it on 2.6.32 kernel, even if the upstream
kernel could fix this automatically (it is hard to track NETIF*
flags), removing it is also safe.

1. https://bugzilla.redhat.com/show_bug.cgi?id=891839



Cc: Jitendra Kalsaria <jitendra.kalsaria@qlogic.com>
Cc: Ron Mercer <ron.mercer@qlogic.com>
Cc: linux-driver@qlogic.com
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Acked-by: Jitendra Kalsaria <jitendra.kalsaria@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>