* Ensure enough ports/phys are available for both the AR8327 and previous
  switches.

* Add some new VLAN HAL methods that will be used by the VLAN configuration
  code.  The AR933x and later switches use slightly different register
  layouts (even though the driver currently doesn't support it.)
Methodize the arswitch VLAN routines.

These differ per chipset family in subtle and evil ways.

It becomes very noticable on the AR8327 where the layout is just plain
wrong.
Add initial AR8327 support.

This is (almost!) enough to actually probe, attach, configure a default
port group and do some basic work.  It's also totally hard-coded for
the Qualcomm Atheros DB120 board - it doesn't yet have any of the code
from OpenWRT which parses extra configuration data to know how to program
the switch.  The LED stuff is also missing.

But, it's enough to facilitate board, PHY, switch and VLAN bringup,
so I am committing it now.

Tested:

* Qualcomm Atheros DB120

Obtained from:	OpenWRT
Link the AR8327 to the build.
Add the AR8327 bits to the DB120 config file.

There's plenty of hints that I haven't yet fleshed out and are hardcoded
in arswitch_8327.c.  They're listed here (from OpenWRT) for completeness.

This is enough to get the thing up, running and pinging.

Note that the mdiobus for the on-switch switch changes - the AR8327
probes first, which exposes mdio1, and thus the arge1 mdiobus will probe
and attach as mdio2.  That is what the AR9344 on-chip switch has to
attach to.

Tested:

* Qualcomm Atheros DB120