net/ipv4: replace simple_strtoul with kstrtoul

Replace simple_strtoul with kstrtoul in three similar occurrences, all setup
handlers:
* route.c: set_rhash_entries
* tcp.c: set_thash_entries
* udp.c: set_uhash_entries

Also check if the conversion failed.

Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 63ddaee..e13546c 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3462,9 +3462,15 @@
 static __initdata unsigned long thash_entries;
 static int __init set_thash_entries(char *str)
 {
+	ssize_t ret;
+
 	if (!str)
 		return 0;
-	thash_entries = simple_strtoul(str, &str, 0);
+
+	ret = kstrtoul(str, 0, &thash_entries);
+	if (ret)
+		return 0;
+
 	return 1;
 }
 __setup("thash_entries=", set_thash_entries);