virtio: Don't use PAGE_SIZE in virtio_pci.c

The virtio PCI devices don't depend on the guest page size.  This matters
now PowerPC virtio is gaining ground (they like 64k pages).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index e37d686..c2cd69b 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -245,7 +245,7 @@
 	}
 
 	/* activate the queue */
-	iowrite32(virt_to_phys(info->queue) >> PAGE_SHIFT,
+	iowrite32(virt_to_phys(info->queue) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT,
 		  vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
 
 	/* create the vring */