irqchip/renesas-rzt2h: Add software-triggered interrupts support

irqchip/renesas-rzt2h: Add software-triggered interrupts support

The Renesas RZ/T2H ICU supports software-triggerable interrupts.

Add a dedicated rzt2h_icu_intcpu_chip irq_chip which implements
rzt2h_icu_intcpu_set_irqchip_state() to allow injecting these
interrupts.

Request the INTCPU IRQs when IRQ injection is enabled to report them
when they occur.

Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260520203117.1516442-3-cosmin-gabriel.tanislav.xa@renesas.com