extcon: Remove duplicate header file in extcon.h

This patch removes the duplicate header file in extcon.h.
Signed-off-by: NChanwoo Choi <cw00.choi@samsung.com>

include/linux/extcon.h

@@ -27,8 +27,6 @@
 #define __LINUX_EXTCON_H__
 
 #include <linux/device.h>
-#include <linux/notifier.h>
-#include <linux/sysfs.h>
 
 /*
  * Define the unique id of supported external connectors