x86/xen: split off enlighten_hvm.c

Move PVHVM related code to enlighten_hvm.c. Three functions:
xen_cpuhp_setup(), xen_reboot(), xen_emergency_restart() are shared, drop
static qualifier from them. These functions will go to common code once
it is split from enlighten.c.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

arch/x86/xen/xen-ops.h

@@ -148,4 +148,12 @@ __visible void xen_adjust_exception_frame(void);
 
 extern int xen_panic_handler_init(void);
 
+int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
+		    int (*cpu_dead_cb)(unsigned int));
+
+void xen_pin_vcpu(int cpu);
+
+void xen_reboot(int reason);
+void xen_emergency_restart(void);
+
 #endif /* XEN_OPS_H */