Merge branch 'ICMP-flow-improvements'

Matteo Croce says:

====================
ICMP flow improvements

This series improves the flow inspector handling of ICMP packets:
The first two patches just add some comments in the code which would have saved
me a few minutes of time, and refactor a piece of code.
The third one adds to the flow inspector the capability to extract the
Identifier field, if present, so echo requests and replies are classified
as part of the same flow.
The fourth patch uses the function introduced earlier to the bonding driver,
so echo replies can be balanced across bonding slaves.

v1 -> v2:
 - remove unused struct members
 - add an helper to check for the Id field
 - use a local flow_dissector_key in the bonding to avoid
   changing behaviour of the flow dissector
====================

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