irqchip/gic-v3-its: Track per-ITS list number

At boot time, we enumerate all the GICv4-capable ITSs, and build
a mask of the available ITSs. Take this opportunity to store
the ITS number in the its_node structure so that we can use it
at a later time.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-gic-v3-its.c

@@ -103,6 +103,7 @@ struct its_node {
 	u64			(*get_msi_base)(struct its_device *its_dev);
 	struct list_head	its_device_list;
 	u64			flags;
+	unsigned long		list_nr;
 	u32			ite_size;
 	u32			device_ids;
 	int			numa_node;
@@ -3064,6 +3065,8 @@ static int __init its_probe_one(struct resource *res,
 			if (err < 0)
 				goto out_free_its;
 
+			its->list_nr = err;
+
 			pr_info("ITS@%pa: Using ITS number %d\n",
 				&res->start, err);
 		} else {