Merge branch 'local-checksum-offload'

Edward Cree says:

====================
Local Checksum Offload

Re-tested VxLAN; everything else is unchanged from v4.

Changes from v4:
 * Rebased series to fix conflicts with vxlan/vxlan6 merge.

Changes from v3:
 * Fixed inverted checksum values introduced in v3.
 * Don't mangle zero checksums in GRE.
 * Clear skb->encapsulation in iptunnel_handle_offloads when not using
   CHECKSUM_PARTIAL, lest drivers incorrectly interpret that as a request
   for inner checksum offload.

Changes from v2:
 * Added support for IPv4 GRE.
 * Split out 'always set up for checksum offload' into its own patch.
 * Removed csum_help from iptunnel_handle_offloads.
 * Rewrote LCO callers to only fold once.
 * Simplified nocheck handling.

Changes from v1:
 * Enabled support in more encapsulation protocols.
   I think it now covers everything except GRE.
 * Wrote up some documentation covering TX checksum offload, LCO and RCO.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>