ARM: New SoC family support

Two new SoC families are added this time.

Sugaya Taichi submitted support for the Milbeaut SoC family from
Socionext and explains:

 "SC2000 is a SoC of the Milbeaut series. equipped with a DSP optimized for
  computer vision. It also features advanced functionalities such as 360-degree,
  real-time spherical stitching with multi cameras, image stabilization for
  without mechanical gimbals, and rolling shutter correction. More detail is
  below:
  https://www.socionext.com/en/products/assp/milbeaut/SC2000.html"

Interestingly, this one has a history dating back to older chips
made by Socionext and previously Matsushita/Panasonic based on their
own mn10300 CPU architecture that was removed from the kernel last year.

Manivannan Sadhasivam adds support for another SoC family, this is the
Bitmain BM1880 chip used in the Sophon Edge TPU developer board.
The chip is intended for Deep Learning applications, and comes
with dual-core Arm Cortex-A53 to run Linux as well as a RISC-V
microcontroller core to control the tensor unit.
For the moment, the TPU is not accessible in mainline Linux, so
we treat it as a generic Arm SoC.
More information is available at https://www.sophon.ai/

Signed-off-by: Arnd Bergmann <arnd@arndb.de>