The classifier configuration for RSS is quite complex, with several
lookup tables being used. This commit adds useful info in debugfs to
see how the different tables are configured :

Added 2 new entries in the per-port directory :

  - .../eth0/default_rxq : The default rx queue on that port
  - .../eth0/rss_enable : Indicates if RSS is enabled in the C2 entry

Added the 'flows' directory :

  It contains one entry per sub-flow. a 'sub-flow' is a unique path from
  Header Parser to the flow table. Multiple sub-flows can point to the
  same 'flow' (each flow has an id from 8 to 29, which is its index in the
  Lookup Id table) :

  - .../flows/00/...
             /01/...
             ...
             /51/id : The flow id. There are 21 unique flows. There's one
                       flow per combination of the following parameters :
                       - L4 protocol (TCP, UDP, none)
                       - L3 protocol (IPv4, IPv6)
                       - L3 parameters (Fragmented or not)
                       - L2 parameters (Vlan tag presence or not)
              .../type : The flow type. This is an even higher level flow,
                         that we manipulate with ethtool. It can be :
                         "udp4" "tcp4" "udp6" "tcp6" "ipv4" "ipv6" "other".
              .../eth0/...
              .../eth1/engine : The hash generation engine used for this
	                        flow on the given port
                  .../hash_opts : The hash generation options indicating on
                                  what data we base the hash (vlan tag, src
                                  IP, src port, etc.)
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>