iavf: fix non-tunneled IPv6 UDP packet type and hashing

iavf: fix non-tunneled IPv6 UDP packet type and hashing

Currently, IAVF's decode_rx_desc_ptype() correctly reports payload type
of L4 for IPv4 UDP packets and IPv{4,6} TCP, but only L3 for IPv6 UDP.
Originally, i40e, ice and iavf were affected.
Commit 73df8c9e3e3d ("i40e: Correct UDP packet header for non_tunnel-ipv6")
fixed that in i40e, then
commit 638a0c8c8861 ("ice: fix incorrect payload indicator on PTYPE")
fixed that for ice.
IPv6 UDP is L4 obviously. Fix it and make iavf report correct L4 hash
type for such packets, so that the stack won't calculate it on CPU when
needs it.

Fixes: 206812b5fccb ("i40e/i40evf: i40e implementation for skb_set_hash")
Reviewed-by: Larysa Zaremba <larysa.zaremba@intel.com>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>