irqchip/riscv-imsic: Convert to msi_create_parent_irq_domain() helper

Now that we have a concise helper to create an MSI parent domain,
switch the RISC-V letter soup over to that.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Nam Cao <tglx@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/b906a38d443577de45923b335d80fc54c5638da0.1750860131.git.namcao@linutronix.de
Link: https://lore.kernel.org/all/20241204124549.607054-6-maz@kernel.org

Author: Marc Zyngier

drivers/irqchip/irq-riscv-imsic-platform.c

@@ -307,6 +307,11 @@ static const struct msi_parent_ops imsic_msi_parent_ops = {
 
 int imsic_irqdomain_init(void)
 {
+	struct irq_domain_info info = {
+		.fwnode		= imsic->fwnode,
+		.ops		= &imsic_base_domain_ops,
+		.host_data	= imsic,
+	};
 	struct imsic_global_config *global;
 
 	if (!imsic || !imsic->fwnode) {
@@ -320,16 +325,11 @@ int imsic_irqdomain_init(void)
 	}
 
 	/* Create Base IRQ domain */
-	imsic->base_domain = irq_domain_create_tree(imsic->fwnode,
-						    &imsic_base_domain_ops, imsic);
+	imsic->base_domain = msi_create_parent_irq_domain(&info, &imsic_msi_parent_ops);
 	if (!imsic->base_domain) {
 		pr_err("%pfwP: failed to create IMSIC base domain\n", imsic->fwnode);
 		return -ENOMEM;
 	}
-	imsic->base_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT;
-	imsic->base_domain->msi_parent_ops = &imsic_msi_parent_ops;
-
-	irq_domain_update_bus_token(imsic->base_domain, DOMAIN_BUS_NEXUS);
 
 	global = &imsic->global;
 	pr_info("%pfwP:  hart-index-bits: %d,  guest-index-bits: %d\n",