x86/ioapic: Create named irq domain

x86/ioapic: Create named irq domain

Use the fwnode to create a named domain so diagnosis works, but only when
the the ioapic is not device tree based.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/20170619235443.752782603@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>