x86: pass in cpu number to switch_to_new_gdt()

Impact: cleanup, prepare for xen boot fix.

Xen needs to call this function very early to setup the GDT and
per-cpu segments.  Remove the call to smp_processor_id() and just
pass in the cpu number.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 0d1e7ac..ef91747 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -122,7 +122,7 @@
 		 * area.  Reload any changed state for the boot CPU.
 		 */
 		if (cpu == boot_cpu_id)
-			switch_to_new_gdt();
+			switch_to_new_gdt(cpu);
 
 		DBG("PERCPU: cpu %4d %p\n", cpu, ptr);
 	}