build: board/ soc: introduce hw model v2 scheme

Hw model v2 scheme offers SoC and  maintainers the possibility to define
promptless SoCs settings which must be selected by the board Kconfig.

Having a board doing `select SOC_<name>` is a much cleaner approach then
selecting the SoC in a configuration file.

It furthermore removes the need to present all SoCs in choice groups, as
the SoC is now an internal setting to Kconfig.

This further has the benefit of not presenting users, especially
new-comers to Zephyr, with SoC selection options in menuconfig which
has potential to cause confusion.

It moves the SOC, SOC_SERIES, and SOC_FAMILY from arch/Kconfig into the
soc Kconfig tree, where they rightfully belongs.

With hw model v2, BOARD name is now passed from the build system to
Kconfig which ensures that the board name used in CMake is always in
sync with the board name used in Kconfig for hw model v2.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>