ipv4: make ip_local_reserved_ports per netns

ip_local_port_range is already per netns, so should ip_local_reserved_ports
be. And since it is none by default we don't actually need it when we don't
enable CONFIG_SYSCTL.

By the way, rename inet_is_reserved_local_port() to inet_is_local_reserved_port()

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

kernel/sysctl.c

@@ -2501,11 +2501,11 @@ int proc_do_large_bitmap(struct ctl_table *table, int write,
 	bool first = 1;
 	size_t left = *lenp;
 	unsigned long bitmap_len = table->maxlen;
-	unsigned long *bitmap = (unsigned long *) table->data;
+	unsigned long *bitmap = *(unsigned long **) table->data;
 	unsigned long *tmp_bitmap = NULL;
 	char tr_a[] = { '-', ',', '\n' }, tr_b[] = { ',', '\n', 0 }, c;
 
-	if (!bitmap_len || !left || (*ppos && !write)) {
+	if (!bitmap || !bitmap_len || !left || (*ppos && !write)) {
 		*lenp = 0;
 		return 0;
 	}