Add the final glue bits required to enable the SPI interface on the
DBAU1550. This is parameterized somewhat as machdep pluggable code, so
different boards can supply different implementations.

At the moment, the DBAU1550 is the only Au1550 board I know of with SPI
connected devices.

I have not enabled I2C on the DBAU1550, as we do not have drivers for either
of the I2C connected devices (a different temperature/voltage sensor and
a serial eeprom.)

branches: 1.8.2; 1.8.8; 1.8.12; 1.8.14; 1.8.16;
Add support for using the MIPS Atheros HAL.
Atheros WLAN added to default evbmips DBAU1500, DBAU1550, and MTX-1 configs.
Note that AR5312 config will require unique HAL that we don't have yet.

Enable PCMCIA on DBAU1550.
Some devices work (an, wdc), while others do not (ne, wi).
However, the bus is useful enough that it makes sense to go ahead and
enable it. Maybe other folks can help me debug the rest of the problems.

branches: 1.6.2; 1.6.4; 1.6.6;
Sort PCI devices alphabetically.
Add "sip" and "fxp" ethernet cards.
Split ethernet and IDE controller devices into separate sections.
Use "options<space><tab>".

branches: 1.5.2;
GPIO support for all supported Alchemy parts.

Add GPIO driver, and GPIO access functions for other subsystems.

Add Au1550 PCI support (Au1500 not yet, coming shortly).
Closes PR port-evbmips/32087.
Reviewed by simonb@ (Also, earlier, matt@, and tsutsui@.)

Clean up DBAU1550 and DBAU1500 (include ALCHEMY) per suggestion from simonb@.

Improved alchemy board support, including board differentiation required for
PCI idsel and irq routing (later).
Various cleanup/rototilling to remove hardcoded pb1000 references.
Reviewed by simonb@, and derived from changes reviewed by matt@ and tsutsui@