genirq: Reuse irq_is_nmi()

Move irq_is_nmi() to the internal header file and reuse it all over the
place.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240423024037.3331215-1-ruanjinjie@huawei.com