soc: nrf: move z_platform_init to a common directory

Use a common implementation for z_platform_init
in nRF SoC family. The implementations are
identical, so no need to maintain separate
identical versions of them. The commit does not
introduce behavioral changes.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
7 files changed