irqchip/gic(v3): Replace gic_irq() with irqd_to_hwirq()

GIC & GIC-v3 share same gic_irq() implementations, both of which serve
exact same purpose as irqd_to_hwirq(). irqd_to_hwirq() is a generic and
top level API of the interrupt subsystem, it's independent of any chip
implementation.

Replace gic_irq() with irqd_to_hwirq() and convert struct irq_data::hwirq
to irq_hw_number_t explicitly.

Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240122085716.2999875-3-dawei.li@shingroup.cn