xen/pci: Move the allocation of IRQs when there are no IOAPIC's to the end

.. which means we can preset of NR_IRQS_LEGACY interrupts using
the 'acpi_get_override_irq' API before this loop.
This means that we can get the IRQ's polarity (and trigger) from either
the ACPI (or MP); or use the default values. This fixes a bug if we did
not have an IOAPIC we would not been able to preset the IRQ's polarity
if the MP table existed.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/pci/xen.c

@@ -441,18 +441,6 @@ int __init pci_xen_initial_domain(void)
 #ifdef CONFIG_ACPI
 	xen_setup_acpi_sci();
 	__acpi_register_gsi = acpi_register_gsi_xen;
-#endif
-	if (0 == nr_ioapics) {
-		for (irq = 0; irq < NR_IRQS_LEGACY; irq++) {
-			pirq = xen_allocate_pirq_gsi(irq);
-			if (WARN(pirq < 0,
-				 "Could not allocate PIRQ for legacy interrupt\n"))
-				break;
-			irq = xen_bind_pirq_gsi_to_irq(irq, pirq, 0, "xt-pic");
-		}
-		return 0;
-	}
-#ifdef CONFIG_ACPI
 	/* Pre-allocate legacy irqs */
 	for (irq = 0; irq < NR_IRQS_LEGACY; irq++) {
 		int trigger, polarity;
@@ -465,6 +453,15 @@ int __init pci_xen_initial_domain(void)
 			true /* allocate IRQ */);
 	}
 #endif
+	if (0 == nr_ioapics) {
+		for (irq = 0; irq < NR_IRQS_LEGACY; irq++) {
+			pirq = xen_allocate_pirq_gsi(irq);
+			if (WARN(pirq < 0,
+				 "Could not allocate PIRQ for legacy interrupt\n"))
+				break;
+			irq = xen_bind_pirq_gsi_to_irq(irq, pirq, 0, "xt-pic");
+		}
+	}
 	return 0;
 }