xenfb: Fix graphic_console_init() build failure

In commit 5643706a09 (console: add head
to index to qemu consoles.) graphic_console_init() was extended to take
an additional argument, but xenfb was not updated accordingly. Fix it.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Don Slutz <dslutz@verizon.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1394228528-31625-1-git-send-email-afaerber@suse.de

hw/display/xenfb.c

@@ -992,7 +992,7 @@ wait_more:
 
     /* vfb */
     fb = container_of(xfb, struct XenFB, c.xendev);
-    fb->c.con = graphic_console_init(NULL, &xenfb_ops, fb);
+    fb->c.con = graphic_console_init(NULL, 0, &xenfb_ops, fb);
     fb->have_console = 1;
 
     /* vkbd */