headers_check fix: linux/nfs_idmap.h

fix the following 'make headers_check' warning:

  usr/include/linux/nfs_idmap.h:55: found __[us]{8,16,32,64} type without #include <linux/types.h>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>

include/linux/nfs_idmap.h

@@ -37,6 +37,8 @@
 #ifndef NFS_IDMAP_H
 #define NFS_IDMAP_H
 
+#include <linux/types.h>
+
 /* XXX from bits/utmp.h  */
 #define IDMAP_NAMESZ  128