irqchip: Use irq_domain_alloc_irqs()

Use the irq_domain_alloc_irqs() wrapper instead of the full
__irq_domain_alloc_irqs() interface, which was only intended for some
legacy (x86) use cases.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20221213140844.15470-2-johan+linaro@kernel.org