Add support for the Goldfish virtual TTY. This is only enough for
early console; the rest will come later.

Add support for the Goldfish virtual programmable interrupt controller.

Re-factor the Goldfish RTC driver into attach-front-end and generic
back-end; Goldfish virtual devices can be found on virtual platforms
that don't use FDT.

Re-factor the Goldfish RTC driver into attach-front-end and generic
back-end; Goldfish virtual devices can be found on virtual platforms
that don't use FDT.