genirq/msi: Populate the domain name if provided by the irqchip

In order to ease debug, let's populate the domain name upfront, before any
MSI gets requested. This allows the domain to appear in the
irq_domain_mapping, and the user to easily find the expected data.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/20170512115538.10767-4-marc.zyngier@arm.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>