ARM: dts: r9a06g032: Add support for GPIO interrupts

ARM: dts: r9a06g032: Add support for GPIO interrupts

In the RZ/N1 SoC, the GPIO interrupts are multiplexed using the GPIO
Interrupt Multiplexer.

Add the multiplexer node and connect GPIO interrupt lines to the
multiplexer.

The interrupt-map available in the multiplexer node has to be updated in
dts files depending on the GPIO usage. Indeed, the usage of an interrupt
for a GPIO is board dependent.

Up to 8 GPIOs can be used as an interrupt line (one per multiplexer
output interrupt).

Signed-off-by: Herve Codina (Schneider Electric) <herve.codina@bootlin.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://patch.msgid.link/20260114093938.1089936-9-herve.codina@bootlin.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>