This adds an ixgbe data structure that is used to determine what
headers:fields can be matched and in what order they are supported.

For hardware devices this can be a bit tricky because typically
only pre-programmed (firmware, ucode, rtl) parse graphs will be
supported and we don't yet have an interface to change these from
the OS. So its sort of a you get whatever your friendly vendor
provides affair at the moment.

In the future we can add the get routines and set routines to
update this data structure. One interesting thing to note here
is the data structure here identifies ethernet, ip, and tcp
fields without having to hardcode them as enumerations or use
other identifiers.
Signed-off-by: NJohn Fastabend <john.r.fastabend@intel.com>
Acked-by: NJamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>