Add support for RX checksum offload of encapsulated packets. This
essentially just means paying attention to the inner checksum flags
in the RX event, and if *either* checksum flag indicates a fail then
don't tell the kernel that checksum offload was successful.
Also, count these checksum errors and export the counts to ethtool -S.
Test the most common "good" case of RX events with a single bitmask
instead of a series of ifs. Move the more specific error checking
in to a separate function for clarity, and don't use unlikely() there
since we know at least one of the bits is bad.
Signed-off-by: Edward Cree <ecree@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>