headers_check fix: linux/igmp.h

fix the following 'make headers_check' warning:

  usr/include/linux/igmp.h:31: found __[us]{8,16,32,64} type without #include <linux/types.h>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>

include/linux/igmp.h

@@ -16,6 +16,7 @@
 #ifndef _LINUX_IGMP_H
 #define _LINUX_IGMP_H
 
+#include <linux/types.h>
 #include <asm/byteorder.h>
 
 /*