MIPS: Loongson-3: Fix BRIDGE irq delivery problem

After commit e509bd7d

 ("genirq: Allow migration of chained
interrupts by installing default action") Loongson-3 fails at here:

setup_irq(LOONGSON_HT1_IRQ, &cascade_irqaction);

This is because both chained_action and cascade_irqaction don't have
IRQF_SHARED flag. This will cause Loongson-3 resume fails because HPET
timer interrupt can't be delivered during S3. So we set the irqchip of
the chained irq to loongson_irq_chip which doesn't disable the chained
irq in CP0.Status.

Cc: stable@vger.kernel.org
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/20434/
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: Huacai Chen <chenhuacai@gmail.com>