irqchip/loongson-liointc: Fix potential dead lock

In the function liointc_set_type(), we need to call the function
irq_gc_unlock_irqrestore() before returning.

Fixes: dbb15226 ("irqchip: Add driver for Loongson I/O Local Interrupt Controller")
Reported-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1594087972-21715-8-git-send-email-yangtiezhu@loongson.cn