net: phonet: mark header_ops as const

Signed-off-by: Lin Zhang <xiaolou4617@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if_phonet.h

@@ -10,5 +10,5 @@
 
 #include <uapi/linux/if_phonet.h>
 
-extern struct header_ops phonet_header_ops;
+extern const struct header_ops phonet_header_ops;
 #endif

net/phonet/af_phonet.c

@@ -149,7 +149,7 @@ static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 	return 1;
 }
 
-struct header_ops phonet_header_ops = {
+const struct header_ops phonet_header_ops = {
 	.create = pn_header_create,
 	.parse = pn_header_parse,
 };