dwc: add receive checksum offload for IPv6

[tuexen]

Summary

This patch adds support for receive checksum offload for TCP/IPv6 and UDP/IPv6. Since receive checksum offload can't be configured separately for IPv4 and IPv6, IFCAP_RXCSUM and IFCAP_RXCSUM_IPV6 can't be changed independently.

[timo.voelker_fh-muenster.de]

Looks good to me.

Since the interface does receive checksum offloading for TCP and UDP over IPv6 already, adding IFCAP_RXCSUM_IPV6 has no functional change. Instead, this lets the interface better report what it does.

Coupling IFCAP_RXCSUM and IFCAP_RXCSUM_IPV6 makes sense since the interface seems to do both or nothing.

sys/dev/dwc/if_dwc.c

616–617

After D54754 has been committed, IFCAP_RXCSUM_IPV6 and IFCAP_TXCSUM_IPV6 can be exchanged by IFCAP_HWCSUM_IPV6.

[tuexen]

sys/dev/dwc/if_dwc.c

616–617

After D54754 has been committed, IFCAP_RXCSUM_IPV6 and IFCAP_TXCSUM_IPV6 can be exchanged by IFCAP_HWCSUM_IPV6.

That is the plan...