irqchip: Add RZ/{T2H,N2H} Interrupt Controller (ICU) driver

irqchip: Add RZ/{T2H,N2H} Interrupt Controller (ICU) driver

The Renesas RZ/T2H (R9A09G077) and Renesas RZ/N2H (R9A09G087) SoCs have an
Interrupt Controller (ICU) that supports interrupts from external pins IRQ0
to IRQ15, and SEI, and software-triggered interrupts INTCPU0 to INTCPU15.

INTCPU0 to INTCPU13, IRQ0 to IRQ13 are non-safety interrupts, while
INTCPU14, INTCPU15, IRQ14, IRQ15 and SEI are safety interrupts, and are
exposed via a separate register space.

Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/20251201112933.488801-3-cosmin-gabriel.tanislav.xa@renesas.com