s390x/pci: use PCI_MSIX_FLAGS on retrieving the MSIX entries

Even PCI_CAP_FLAGS has the same value as PCI_MSIX_FLAGS, the later one is
the more proper on retrieving MSIX entries.

This patch uses PCI_MSIX_FLAGS to retrieve the MSIX entries.
Signed-off-by: NWei Yang <richard.weiyang@gmail.com>
CC: Cornelia Huck <cornelia.huck@de.ibm.com>
CC: Christian Borntraeger <borntraeger@de.ibm.com>
Message-Id: <1455895091-7589-3-git-send-email-richard.weiyang@gmail.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>

hw/s390x/s390-pci-bus.c

@@ -524,7 +524,7 @@ static int s390_pcihost_setup_msix(S390PCIBusDevice *pbdev)
         return 0;
     }
 
-    ctrl = pci_host_config_read_common(pbdev->pdev, pos + PCI_CAP_FLAGS,
+    ctrl = pci_host_config_read_common(pbdev->pdev, pos + PCI_MSIX_FLAGS,
              pci_config_size(pbdev->pdev), sizeof(ctrl));
     table = pci_host_config_read_common(pbdev->pdev, pos + PCI_MSIX_TABLE,
              pci_config_size(pbdev->pdev), sizeof(table));