virtio-pci: add missing 'static'

There are no outside references to virtio_portio.
Add missing 'static' specifier.

Reviewed-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 4a4413d..8a931ce 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -491,7 +491,7 @@
     virtio_config_writel(proxy->vdev, addr, val);
 }
 
-const MemoryRegionPortio virtio_portio[] = {
+static const MemoryRegionPortio virtio_portio[] = {
     { 0, 0x10000, 1, .write = virtio_pci_config_writeb, },
     { 0, 0x10000, 2, .write = virtio_pci_config_writew, },
     { 0, 0x10000, 4, .write = virtio_pci_config_writel, },