dt-bindings: arm: fsl: Add NXP S32N79 SoC and RDB board

dt-bindings: arm: fsl: Add NXP S32N79 SoC and RDB board

Add device tree binding documentation for the NXP S32N79 automotive SoC
and the S32N79 Reference Design Board (S32N79-RDB).

The S32N79 is an automotive-grade SoC featuring eight ARM Cortex-A78AE
cores organized for high-performance networking and gateway applications
in vehicles.

Co-developed-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@oss.nxp.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>