cfg80211: remove duplicated #include

Remove duplicated #include in include/net/cfg80211.h.
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/cfg80211.h

@@ -10,7 +10,6 @@
 #include <net/iw_handler.h>
 #include <net/genetlink.h>
 /* remove once we remove the wext stuff */
-#include <net/iw_handler.h>
 
 /*
  * 802.11 configuration in-kernel interface