x86/pci/intel_mid_pci: Propagate actual return code

mp_map_gsi_to_irq() returns different codes if it fails.
intel_mid_pci_irq_enable() hides this under -EBUSY.

Return the actual failure code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Link: http://lkml.kernel.org/r/1438161409-4671-3-git-send-email-andriy.shevchenko@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/pci/intel_mid_pci.c

@@ -213,6 +213,7 @@ static int intel_mid_pci_irq_enable(struct pci_dev *dev)
 {
 	struct irq_alloc_info info;
 	int polarity;
+	int ret;
 
 	if (dev->irq_managed && dev->irq > 0)
 		return 0;
@@ -244,8 +245,9 @@ static int intel_mid_pci_irq_enable(struct pci_dev *dev)
 	 * MRST only have IOAPIC, the PCI irq lines are 1:1 mapped to
 	 * IOAPIC RTE entries, so we just enable RTE for the device.
 	 */
-	if (mp_map_gsi_to_irq(dev->irq, IOAPIC_MAP_ALLOC, &info) < 0)
-		return -EBUSY;
+	ret = mp_map_gsi_to_irq(dev->irq, IOAPIC_MAP_ALLOC, &info);
+	if (ret < 0)
+		return ret;
 
 	dev->irq_managed = 1;