irqchip/loongson-pch-pic: Fix registration of syscore_ops

When support suspend/resume for loongson-pch-pic, the syscore_ops
is registered twice in dual-bridges machines where there are two
pch-pic IRQ domains. Repeated registration of an same syscore_ops
broke syscore_ops_list, so the patch will corret it.

Fixes: 1ed008a ("irqchip/loongson-pch-pic: Add suspend/resume support")
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>

Author: lvjianmin-loongson

drivers/irqchip/irq-loongson-pch-pic.c

@@ -311,7 +311,8 @@ static int pch_pic_init(phys_addr_t addr, unsigned long size, int vec_base,
 	pch_pic_handle[nr_pics] = domain_handle;
 	pch_pic_priv[nr_pics++] = priv;
 
-	register_syscore_ops(&pch_pic_syscore_ops);
+	if (nr_pics == 1)
+		register_syscore_ops(&pch_pic_syscore_ops);
 
 	return 0;