irqchip/loongson-liointc: Add IRQCHIP_SKIP_SET_WAKE flag

LIOINTC doesn't require specific logic to work with wakeup IRQs,
and no irq_set_wake callback is needed. To allow registered IRQs
from LIOINTC to be used as a wakeup-source, and ensure irq_set_irq_wake()
works well, the flag IRQCHIP_SKIP_SET_WAKE should be added.

Reviewed-by: Huacai Chen <chenhuacai@kernel.org>
Signed-off-by: Yinbo Zhu <zhuyinbo@loongson.cn>
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230614115936.5950-5-lvjianmin@loongson.cn