extcon: Add missing header file to extcon.h

This patch add missing header file(sysfs.h/device.h) to extcon.h
because 'struct extcon_dev' define attribute field(attr_g_muex/
attrs_muex/d_attrs_mues) and device_type field(extcon_dev_type).
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>

include/linux/extcon.h

@@ -23,7 +23,9 @@
 #ifndef __LINUX_EXTCON_H__
 #define __LINUX_EXTCON_H__
 
+#include <linux/device.h>
 #include <linux/notifier.h>
+#include <linux/sysfs.h>
 
 #define SUPPORTED_CABLE_MAX	32
 #define CABLE_NAME_MAX		30