Extcon: Staticise extcon_class

It's not referenced outside the core file.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/extcon/extcon_class.c b/drivers/extcon/extcon_class.c
index f598a70..99f7227 100644
--- a/drivers/extcon/extcon_class.c
+++ b/drivers/extcon/extcon_class.c
@@ -65,7 +65,7 @@
 	NULL,
 };
 
-struct class *extcon_class;
+static struct class *extcon_class;
 #if defined(CONFIG_ANDROID)
 static struct class_compat *switch_class;
 #endif /* CONFIG_ANDROID */