netfilter: fix warning about invalid const usage

This patch fixes the declaration of the logger structure in ebt_log
and ebt_ulog: I forgot to remove the const option from their declaration
in the commit ca735b3aaa945626ba65a3e51145bfe4ecd9e222 ("netfilter:
use a linked list of loggers").

Pointed-out-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Eric Leblond <eric@inl.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/netfilter/ebt_ulog.c b/net/bridge/netfilter/ebt_ulog.c
index 2c6d682..80c78c5 100644
--- a/net/bridge/netfilter/ebt_ulog.c
+++ b/net/bridge/netfilter/ebt_ulog.c
@@ -279,7 +279,7 @@
 	.me		= THIS_MODULE,
 };
 
-static const struct nf_logger ebt_ulog_logger = {
+static struct nf_logger ebt_ulog_logger __read_mostly = {
 	.name		= "ulog",
 	.logfn		= &ebt_log_packet,
 	.me		= THIS_MODULE,