netfilter: cleanup printk messages

Make sure all printk messages have a severity level.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/ipv4/netfilter/iptable_filter.c b/net/ipv4/netfilter/iptable_filter.c
index 5539246..c37641e 100644
--- a/net/ipv4/netfilter/iptable_filter.c
+++ b/net/ipv4/netfilter/iptable_filter.c
@@ -89,7 +89,7 @@
 	int ret;
 
 	if (forward < 0 || forward > NF_MAX_VERDICT) {
-		printk("iptables forward must be 0 or 1\n");
+		pr_err("iptables forward must be 0 or 1\n");
 		return -EINVAL;
 	}