irq/irqdomain: Update __irq_domain_alloc_fwnode() function documentation

A recent commit changed a parameter of __irq_domain_alloc_fwnode(), but
did not update the documentation comment. Fix it up.

Fixes: b977fcf4 ("irqdomain/debugfs: Use PAs to generate fwnode names")
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1571476047-29463-1-git-send-email-wang.yi59@zte.com.cn

kernel/irq/irqdomain.c

@@ -51,7 +51,7 @@ EXPORT_SYMBOL_GPL(irqchip_fwnode_ops);
  * @type:	Type of irqchip_fwnode. See linux/irqdomain.h
  * @name:	Optional user provided domain name
  * @id:		Optional user provided id if name != NULL
- * @data:	Optional user-provided data
+ * @pa:		Optional user-provided physical address
  *
  * Allocate a struct irqchip_fwid, and return a poiner to the embedded
  * fwnode_handle (or NULL on failure).