genirq/proc: Use irq_move_pending() in show_irq_affinity()

irq_move_pending() encapsulates irqd_is_setaffinity_pending() depending on
CONFIG_GENERIC_PENDING_IRQ.

Replace the open coded #ifdeffery with it.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240829111522.230595-1-ruanjinjie@huawei.com