net: Fix too optimistic NETIF_F_HW_CSUM features

NETIF_F_HW_CSUM is a superset of NETIF_F_IP_CSUM+NETIF_F_IPV6_CSUM, but
some drivers miss the difference. Fix this and also fix UFO dependency
on checksumming offload as it makes the same mistake in assumptions.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: Jon Mason <jon.mason@exar.com>
Signed-off-by: David S. Miller <davem@davemloft.net>