soc: arm: nxp: cleanup in soc.h headers

A commit that organizes the soc.h header of NXP SoCs:
- removing redundant inclusions of sys/util.h
- removing inclusions of device.h and kernel_includes.h
- including the auto-generated DTS board header
- including the fsl_common.h header
- fixing minor style issues

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