xen64: define asm/xen/interface for 64-bit

Copy 64-bit definitions of various interface structures into place.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/xen/interface/callback.h b/include/xen/interface/callback.h
index 4aadcba..2ae3cd2 100644
--- a/include/xen/interface/callback.h
+++ b/include/xen/interface/callback.h
@@ -82,9 +82,9 @@
  */
 #define CALLBACKOP_register                0
 struct callback_register {
-    uint16_t type;
-    uint16_t flags;
-    struct xen_callback address;
+	uint16_t type;
+	uint16_t flags;
+	xen_callback_t address;
 };
 
 /*