arch/x86/kernel/cpu/common.c: fix unused symbol warning

x86_64 allnoconfig:

arch/x86/kernel/cpu/common.c:968: warning: 'syscall32_cpu_init' defined but not used

Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/kernel/cpu/common.c

@@ -964,6 +964,7 @@ static void vgetcpu_set_mode(void)
 		vgetcpu_mode = VGETCPU_LSL;
 }
 
+#ifdef CONFIG_IA32_EMULATION
 /* May not be __init: called during resume */
 static void syscall32_cpu_init(void)
 {
@@ -975,7 +976,8 @@ static void syscall32_cpu_init(void)
 
 	wrmsrl(MSR_CSTAR, ia32_cstar_target);
 }
-#endif
+#endif		/* CONFIG_IA32_EMULATION */
+#endif		/* CONFIG_X86_64 */
 
 #ifdef CONFIG_X86_32
 void enable_sep_cpu(void)