xen: Use this_cpu_ops

Use this_cpu_ops to reduce code size and simplify things in various places.

V3->V4:
	Move instance of this_cpu_inc_return to a later patchset so that
	this patch can be applied without infrastructure changes.

Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 44dcad4..aa8c89a 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -574,8 +574,8 @@
 
 	preempt_disable();
 
-	start = __get_cpu_var(idt_desc).address;
-	end = start + __get_cpu_var(idt_desc).size + 1;
+	start = __this_cpu_read(idt_desc.address);
+	end = start + __this_cpu_read(idt_desc.size) + 1;
 
 	xen_mc_flush();