genirq/debugfs: Remove redundant NULL pointer check

debugfs_remove() can be called with a NULL pointer.

Fixes: 087cdfb662ae5 ("genirq/debugfs: Add proper debugfs interface")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/irq/irqdomain.c

@@ -1667,8 +1667,7 @@ static void debugfs_add_domain_dir(struct irq_domain *d)
 
 static void debugfs_remove_domain_dir(struct irq_domain *d)
 {
-	if (d->debugfs_file)
-		debugfs_remove(d->debugfs_file);
+	debugfs_remove(d->debugfs_file);
 }
 
 void __init irq_domain_debugfs_init(struct dentry *root)