Merge branch 'net-More-movement-to-fib_nh_common'

David Ahern says:

====================
net: More movement to fib_nh_common

Second set of three with the end goal of enabling IPv6 gateways with IPv4
routes.

This set moves:
- the ipv4 tracepoint to take a fib_nh_common and updates it to handle
  a v6 gateway.
- consolidates route notifications to use the same fill functions
  for both ipv4 and ipv6

v4
- enhanced the commit message for patches 1 and 2

v3
- comments from Martin:
  + renamed FIB_RES_NH to FIB_RES_NHC
  + removed family check from fib_result_prefsrc
  + in fib_nexthop_info, renamed nexthop arg to nhc and dropped for_ipv4 arg

v2
- dropped patches moving cached routes and exception buckets to
  fib_nh_common. The goal is allowing a fib6_nh to be used with an
  IPv4 route. The hold up is the need for separate exception buckets -
  one for v6 routes and one for v4 routes. When all of the nexthop patches
  are in, adding a secondi exception bucket pushes IPv6 fib6_info
  allocations over 256 which means fib6_info allocations roll up to 512.
  Hence, deferring the patches until some data mining can be done to keep
  the allocations at 256.
====================

Acked-by: Martin KaFai Lau <[email protected]>
Signed-off-by: David S. Miller <[email protected]>