Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Now that we are fully FDT-driven on MRVL platforms, remove PHYSMEM_SIZE option.

Introduce basic support for Marvell families of system-on-chip ARM devices:

* Orion
- 88F5181
- 88F5182
- 88F5281

* Kirkwood
- 88F6281

* Discovery
- MV78100

The above families of SOCs are built around CPU cores compliant with ARMv5TE
instruction set architecture definition. They share a number of integrated
peripherals. This commit brings support for the following basic elements:

* GPIO
* Interrupt controller
* L1, L2 cache
* Timers, watchdog, RTC
* TWSI (I2C)
* UART

Other peripherals drivers will be introduced separately.

Reviewed by: imp, marcel, stass (Thanks guys!)
Obtained from: Marvell, Semihalf