x86: irq: Fix placement of mp_should_keep_irq()

While f3761db164 ("x86, irq: Fix build error caused by
9eabc99a635a77cbf09") addressed the original build problem,
declaration, inline stub, and definition still seem misplaced: It isn't
really IO-APIC related, and it's being used solely in arch/x86/pci/.
This also means stubbing it out when !CONFIG_X86_IO_APIC was at least
questionable.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Link: http://lkml.kernel.org/r/545747BE020000780004436E@mail.emea.novell.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/pci/irq.c

@@ -1254,6 +1254,18 @@ static int pirq_enable_irq(struct pci_dev *dev)
 	return 0;
 }
 
+bool mp_should_keep_irq(struct device *dev)
+{
+	if (dev->power.is_prepared)
+		return true;
+#ifdef CONFIG_PM_RUNTIME
+	if (dev->power.runtime_status == RPM_SUSPENDING)
+		return true;
+#endif
+
+	return false;
+}
+
 static void pirq_disable_irq(struct pci_dev *dev)
 {
 	if (io_apic_assign_pci_irqs && !mp_should_keep_irq(&dev->dev) &&