xen: make dummy_shared_info non-static

Rename dummy_shared_info to xen_dummy_shared_info and make it
non-static, in anticipation of users outside of enlighten.c

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 7bdc8c5..826d6e4 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -15,6 +15,7 @@
 DECLARE_PER_CPU(unsigned long, xen_current_cr3);
 
 extern struct start_info *xen_start_info;
+extern struct shared_info xen_dummy_shared_info;
 extern struct shared_info *HYPERVISOR_shared_info;
 
 char * __init xen_memory_setup(void);