xen: events: mark cpu_evtchn_mask_p as __refdata

This variable starts out pointing at init_evtchn_mask which is marked
__initdata but is set to point to a non-init data region in xen_init_IRQ
which is itself an __init function so this is safe.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Tested-and-acked-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/xen/events.c

@@ -114,7 +114,7 @@ struct cpu_evtchn_s {
 static __initdata struct cpu_evtchn_s init_evtchn_mask = {
 	.bits[0 ... (NR_EVENT_CHANNELS/BITS_PER_LONG)-1] = ~0ul,
 };
-static struct cpu_evtchn_s *cpu_evtchn_mask_p = &init_evtchn_mask;
+static struct cpu_evtchn_s __refdata *cpu_evtchn_mask_p = &init_evtchn_mask;
 
 static inline unsigned long *cpu_evtchn_mask(int cpu)
 {