PCI MSI: Unmask MSI if setup failed

The initial state of mask register of MSI is unmasked.  We set it
masked before calling arch_setup_msi_irqs().  If arch_setup_msi_irq()
fails, it is better to restore the state of the mask register.
Reviewed-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/msi.c

@@ -383,6 +383,7 @@ static int msi_capability_init(struct pci_dev *dev, int nvec)
 	/* Configure MSI capability structure */
 	ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSI);
 	if (ret) {
+		msi_mask_irq(entry, mask, ~mask);
 		msi_free_irqs(dev);
 		return ret;
 	}