Add support for two new winbond SPI flash parts.

The 8devices carambola 2 board uses the 16MB part.

Here's how it looks:

spibus0: <spibus bus> on spi0
mx25l0: <M25Pxx Flash Family> at cs 0 on spibus0
mx25l0: w25q128, sector 65536 bytes, 256 sectors

Tested:

* 8devices Carambola 2 board
Add 8devices CARAMBOLA2 support.

This is based on the AR933x (Hornet) SoC from Qualcomm Atheros.

It's a much nicer board to do development on - 64MB RAM, 16MB flash.
The development board breaks out the GPIO pins, ethernet, serial (via
a USB<->RS232 chip), USB host and of course a small wifi antenna.

Everything but the wifi works thus far.