netfilter: use pr_perror only when errno has to be printed

Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/netfilter.c

@@ -85,7 +85,7 @@ static int nf_connection_switch_raw(int family, u32 *src_addr, u16 src_port,
 	 */
 	ret = cr_system(-1, -1, -1, "sh", argv, 0);
 	if (ret < 0 || !WIFEXITED(ret) || WEXITSTATUS(ret)) {
-		pr_perror("Iptables configuration failed");
+		pr_err("Iptables configuration failed\n");
 		return -1;
 	}