netfilter: nf_log: fix sparse warning in nf_logger_find_get()

net/netfilter/nf_log.c:157:16: warning: incorrect type in assignment (different address spaces)
net/netfilter/nf_log.c:157:16:    expected struct nf_logger *logger
net/netfilter/nf_log.c:157:16:    got struct nf_logger [noderef] <asn:4>*<noident>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_log.c

@@ -154,8 +154,7 @@ int nf_logger_find_get(int pf, enum nf_log_type type)
 	struct nf_logger *logger;
 	int ret = -ENOENT;
 
-	logger = loggers[pf][type];
-	if (logger == NULL)
+	if (rcu_access_pointer(loggers[pf][type]) == NULL)
 		request_module("nf-logger-%u-%u", pf, type);
 
 	rcu_read_lock();