soc: nxp_s32: introduce support for S32K1 devices

Introduce support for NXP S32K1 family of 32-bit MCUs, and
particularly for S32K146 devices. S32K1 share a fair amount of
similarities with Kinetis family, so most of the peripheral drivers
can be reused.

Signed-off-by: Manuel Argüelles <manuel.arguelles@nxp.com>