hw/arm: Add two NPCM7xx-based machines

hw/arm: Add two NPCM7xx-based machines

This adds two new machines, both supported by OpenBMC:

  - npcm750-evb: Nuvoton NPCM750 Evaluation Board.
  - quanta-gsj: A board with a NPCM730 chip.

They rely on the NPCM7xx SoC device to do the heavy lifting. They are
almost completely identical at the moment, apart from the SoC type,
which currently only changes the reset contents of one register
(GCR.MDLR), but they might grow apart a bit more as more functionality
is added.

Both machines can boot the Linux kernel into /bin/sh.

Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Alexander Bulekov <alxndr@bu.edu>
Signed-off-by: Havard Skinnemoen <hskinnemoen@google.com>
Message-id: 20200911052101.2602693-6-hskinnemoen@google.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>