net: aquantia: fix rx checksum offload for UDP/TCP over IPv6

TCP/UDP checksum validity was propagated to skb
only if IP checksum is valid.
But for IPv6 there is no validity as there is no checksum in IPv6.
This patch propagates TCP/UDP checksum validity regardless of IP checksum.

Fixes: 018423e9 ("net: ethernet: aquantia: Add ring support code")
Signed-off-by: Igor Russkikh <igor.russkikh@aquantia.com>
Signed-off-by: Nikita Danilov <nikita.danilov@aquantia.com>
Signed-off-by: Dmitry Bogdanov <dmitry.bogdanov@aquantia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>