[ACPI] delete extraneous IRQ->pin mappings below IRQ 16

http://bugzilla.kernel.org/show_bug.cgi?id=2408

arch/i386/kernel/io_apic.c

@@ -2440,6 +2440,10 @@ int io_apic_set_pci_routing (int ioapic, int pin, int irq, int edge_level, int a
 	entry.polarity = active_high_low;
 	entry.mask  = 1;
 
+	/*
+	 * IRQs < 16 are already in the irq_2_pin[] map
+	 */
+	if (irq >= 16)
 		add_pin_to_irq(irq, ioapic, pin);
 
 	entry.vector = assign_irq_vector(irq);

arch/x86_64/kernel/io_apic.c

@@ -1891,6 +1891,10 @@ int io_apic_set_pci_routing (int ioapic, int pin, int irq, int edge_level, int a
 	entry.polarity = active_high_low;
 	entry.mask = 1;					 /* Disabled (masked) */
 
+	/*
+	 * IRQs < 16 are already in the irq_2_pin[] map
+	 */
+	if (irq >= 16)
 		add_pin_to_irq(irq, ioapic, pin);
 
 	entry.vector = assign_irq_vector(irq);