x86/nmi: export local_touch_nmi() symbol for modules

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index f84f5c5..6030805 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -509,3 +509,4 @@
 {
 	__this_cpu_write(last_nmi_rip, 0);
 }
+EXPORT_SYMBOL_GPL(local_touch_nmi);