[NETLINK]: Mark netlink policies const

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 9ad1f62..311d633 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -441,7 +441,7 @@
 	return -EINVAL;
 }
 
-struct nla_policy rtm_ipv4_policy[RTA_MAX+1] __read_mostly = {
+const struct nla_policy rtm_ipv4_policy[RTA_MAX+1] = {
 	[RTA_DST]		= { .type = NLA_U32 },
 	[RTA_SRC]		= { .type = NLA_U32 },
 	[RTA_IIF]		= { .type = NLA_U32 },