xen nic: use XC_PAGE_SIZE instead of PAGE_SIZE.

Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/xen_nic.c

@@ -176,7 +176,7 @@ static void net_tx_packets(struct XenNetDev *netdev)
 	    if (txreq.flags & NETTXF_csum_blank) {
                 /* have read-only mapping -> can't fill checksum in-place */
                 if (!tmpbuf)
-                    tmpbuf = qemu_malloc(PAGE_SIZE);
+                    tmpbuf = qemu_malloc(XC_PAGE_SIZE);
                 memcpy(tmpbuf, page + txreq.offset, txreq.size);
 		net_checksum_calculate(tmpbuf, txreq.size);
                 qemu_send_packet(netdev->vs, tmpbuf, txreq.size);