dt-bindings: interrupt-controller: fsl,irqsteer: add S32N79 support

dt-bindings: interrupt-controller: fsl,irqsteer: add S32N79 support

Add compatible string for the interrupt steering controller used in NXP
S32N79 SoC.

The S32N79 SoC differs from the i.MX version by not implementing the
CHANCTRL register, but otherwise maintains the same programming model and
register layout.

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>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>