genirq: Move irq_chip_write_msi_msg() helper to core

No point to expose this to the world. The only legitimate user is the
core code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>

kernel/irq/msi.c

@@ -32,6 +32,12 @@ void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)
 EXPORT_SYMBOL_GPL(get_cached_msi_msg);
 
 #ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN
+static inline void irq_chip_write_msi_msg(struct irq_data *data,
+					  struct msi_msg *msg)
+{
+	data->chip->irq_write_msi_msg(data, msg);
+}
+
 /**
  * msi_domain_set_affinity - Generic affinity setter function for MSI domains
  * @irq_data:	The irq data associated to the interrupt