genetlink: make genl_info->nlhdr const

struct netlink_callback has a const nlh pointer, make the
pointer in struct genl_info const as well, to make copying
between the two easier.
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20230814214723.2924989-3-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/genetlink.h

@@ -104,7 +104,7 @@ struct genl_family {
 struct genl_info {
 	u32			snd_seq;
 	u32			snd_portid;
-	struct nlmsghdr *	nlhdr;
+	const struct nlmsghdr *	nlhdr;
 	struct genlmsghdr *	genlhdr;
 	void *			userhdr;
 	struct nlattr **	attrs;

net/ncsi/ncsi-netlink.c

@@ -563,7 +563,7 @@ int ncsi_send_netlink_timeout(struct ncsi_request *nr,
 int ncsi_send_netlink_err(struct net_device *dev,
 			  u32 snd_seq,
 			  u32 snd_portid,
-			  struct nlmsghdr *nlhdr,
+			  const struct nlmsghdr *nlhdr,
 			  int err)
 {
 	struct nlmsghdr *nlh;

net/ncsi/ncsi-netlink.h

@@ -19,7 +19,7 @@ int ncsi_send_netlink_timeout(struct ncsi_request *nr,
 int ncsi_send_netlink_err(struct net_device *dev,
 			  u32 snd_seq,
 			  u32 snd_portid,
-			  struct nlmsghdr *nlhdr,
+			  const struct nlmsghdr *nlhdr,
 			  int err);
 
 #endif /* __NCSI_NETLINK_H__ */