Merge branch 'dsa-use-per-port-upstream-port'

Vivien Didelot says:

====================
net: dsa: use per-port upstream port

An upstream port is a local switch port used to reach a CPU port.

DSA still considers a unique CPU port in the whole switch fabric and
thus return a unique upstream port for a given switch. This is wrong in
a multiple CPU ports environment.

We are now switching to using the dedicated CPU port assigned to each
port in order to get rid of the deprecated unique tree CPU port.

This patchset makes the dsa_upstream_port() helper take a port argument
and goes one step closer complete support for multiple CPU ports.

Changes in v2:
  - reverse-christmas-tree-fy variables
====================

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