Merge branch 'dsa-master-and-slave-helpers'

Vivien Didelot says:

====================
net: dsa: master and slave helpers

This patch series adds a few helpers to DSA core for clarity and
readability but brings no functional changes.

A dsa_slave_notify helper calls the DSA notifiers when (un)registering a
slave device.

Most of the DSA slave code only needs to access the dsa_port structure,
not the dsa_slave_priv (which only contains a few PHY-specific members).
Thus a dsa_slave_to_port helper returns a dsa_port structure of a slave
device.

A dsa_slave_to_master returns the master device of a slave device.

After that the netdev member of the dsa_port structure is split into two
explicit master and slave members to avoid confusion, and a dsa_to_port
helper is added for switch drivers to get a const reference to a port.

Changes in v2:
  - prefer dsa_slave_to_master instead of dsa_slave_get_master
  - rename dsa_master_get_slave to dsa_master_find_slave
  - pack master and slave net devices into an anonymous union
  - add dsa_to_port public helper for switch drivers
  - add Reviewed-by tags from Florian
====================

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