netfilter: headers_check fix: linux/netfilter/xt_osf.h

fix the following 'make headers_check' warnings:

  usr/include/linux/netfilter/xt_osf.h:40: found __[us]{8,16,32,64} type without #include <linux/types.h>

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>