Merge branch 'dsa_ptr-port'

Vivien Didelot says:

====================
net: dsa: change dsa_ptr for a dsa_port

With DSA, a master net_device is physically wired to a dedicated CPU
switch port. For interaction with the DSA layer, the struct net_device
contains a dsa_ptr, which currently points to a dsa_switch_tree object.

This is only valid for a switch fabric with a single CPU port. In order
to support switch fabrics with multiple CPU ports, we first need to
change the type of dsa_ptr to what it really is: a dsa_port object.

This is what this patchset does. The first patches adds a
dsa_master_get_slave helper and cleans up portions of DSA core to make
the next patches more readable. These next patches prepare the xmit and
receive hot paths and finally change dsa_ptr.

Changes in v2:
  - introduce dsa_master_get_slave helper to simplify patch 6
  - keep hot path data at beginning of dsa_port for cacheline 1
====================

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