genirq/manage: Rework irq_set_parent()

Use the new guards to get and lock the interrupt descriptor and tidy up the
code.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20250429065422.258216558@linutronix.de

Author: KAGA-KOKO

kernel/irq/manage.c

@@ -959,16 +959,11 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned long flags)
 #ifdef CONFIG_HARDIRQS_SW_RESEND
 int irq_set_parent(int irq, int parent_irq)
 {
-	unsigned long flags;
-	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
-
-	if (!desc)
-		return -EINVAL;
-
-	desc->parent_irq = parent_irq;
-
-	irq_put_desc_unlock(desc, flags);
-	return 0;
+	scoped_irqdesc_get_and_lock(irq, 0) {
+		scoped_irqdesc->parent_irq = parent_irq;
+		return 0;
+	}
+	return -EINVAL;
 }
 EXPORT_SYMBOL_GPL(irq_set_parent);
 #endif