Merge initial Sophgo patches into riscv-dt-for-next

Two series, from Chen and Jisheng, to add support for some of Sophgo's
offerings - albeit on vastly different ends of the spectrum. The sg2042
is a "developer motherboard" with a 64 core SoC. The cv1800 series are
aimed for use in IP cameras, as far as I can tell, and have one core for
running Linux on.

I expect that Chen Wang will take over maintenance of these SoCs once
they have got more used to the process etc, and in the meantime I will
apply the patches and send them to the soc maintainers. At least, that
was what they requested I do :)

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>