platform-msi: Export symbol platform_msi_create_irq_domain()

Allow irqchip drivers using platform MSI to be built as modules.
Signed-off-by: Frank Li <Frank.Li@nxp.com>
[maz: rewrote commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220922161246.20586-2-Frank.Li@nxp.com

drivers/base/platform-msi.c

@@ -138,6 +138,7 @@ struct irq_domain *platform_msi_create_irq_domain(struct fwnode_handle *fwnode,
 
 	return domain;
 }
+EXPORT_SYMBOL_GPL(platform_msi_create_irq_domain);
 
 static int platform_msi_alloc_priv_data(struct device *dev, unsigned int nvec,
 					irq_write_msi_msg_t write_msi_msg)