Device Tree port

TODO:

• gpio
• gpio irq
• ok-led (needs gpio)
• vcio
• fb (needs vcio)
• dma
• power
• usb (needs dma, power)
• ethernet mac address
• mmc/emmc (aka sdhci)
• pinmux (needed by everything that uses a configurable pin)
• spi
• spi irq
• spi dma
• i2c
• i2c irq
• i2c dma
• audio
• pwm
• vc-mem
• vchiq (aka vc04/vcos)