dt-bindings: soc: renesas: Document RZ/N1 GPIO Interrupt Multiplexer

dt-bindings: soc: renesas: Document RZ/N1 GPIO Interrupt Multiplexer

On the Renesas RZ/N1 SoC, GPIOs can generate interruptions. Those
interruption lines are multiplexed by the GPIO Interrupt Multiplexer in
order to map 32 * 3 GPIO interrupt lines to 8 GIC interrupt lines.

The GPIO interrupt multiplexer IP does nothing but select 8 GPIO
IRQ lines out of the 96 available to wire them to the GIC input lines.

Signed-off-by: Herve Codina (Schneider Electric) <herve.codina@bootlin.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260114093938.1089936-7-herve.codina@bootlin.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>