x86: load new GDT after setting up boot cpu per-cpu area

Impact: sync 32 and 64-bit code

Merge load_gs_base() into switch_to_new_gdt().  Load the GDT and
per-cpu state for the boot cpu when its new area is set up.

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 bcca3a7..4caa78d 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -113,13 +113,13 @@
 		per_cpu(x86_cpu_to_node_map, cpu) =
 				early_per_cpu_map(x86_cpu_to_node_map, cpu);
 #endif
+#endif
 		/*
 		 * Up to this point, the boot CPU has been using .data.init
-		 * area.  Reload %gs offset for the boot CPU.
+		 * area.  Reload any changed state for the boot CPU.
 		 */
 		if (cpu == boot_cpu_id)
-			load_gs_base(cpu);
-#endif
+			switch_to_new_gdt();
 
 		DBG("PERCPU: cpu %4d %p\n", cpu, ptr);
 	}