[XFRM]: xfrm_larval_drop sysctl should be __read_mostly.

#include <net/xfrm.h>

#include <net/ip.h>

#include <linux/audit.h>

#include <linux/cache.h>

#include "xfrm_hash.h"

int sysctl_xfrm_larval_drop;

int sysctl_xfrm_larval_drop __read_mostly;

DEFINE_MUTEX(xfrm_cfg_mutex);

EXPORT_SYMBOL(xfrm_cfg_mutex);