genirq/irqdomain: Update irq_domain_ops.activate() signature

The irq_domain_ops.activate() callback has no return value and no way to
tell the function that the activation is early.

The upcoming changes to support a reservation scheme which allows to assign
interrupt vectors on x86 only when the interrupt is actually requested
requires:

  - A return value, so activation can fail at request_irq() time
  
  - Information that the activate invocation is early, i.e. before
    request_irq().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Yu Chen <yu.c.chen@intel.com>
Acked-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Len Brown <lenb@kernel.org>
Link: https://lkml.kernel.org/r/20170913213152.848490816@linutronix.de

drivers/iommu/intel_irq_remapping.c

@@ -1389,12 +1389,13 @@ static void intel_irq_remapping_free(struct irq_domain *domain,
 	irq_domain_free_irqs_common(domain, virq, nr_irqs);
 }
 
-static void intel_irq_remapping_activate(struct irq_domain *domain,
-					 struct irq_data *irq_data)
+static int intel_irq_remapping_activate(struct irq_domain *domain,
+					struct irq_data *irq_data, bool early)
 {
 	struct intel_ir_data *data = irq_data->chip_data;
 
 	modify_irte(&data->irq_2_iommu, &data->irte_entry);
+	return 0;
 }
 
 static void intel_irq_remapping_deactivate(struct irq_domain *domain,