[PATCH] netlink: update outdated comment

[Kexin Sun]

The function netlink_clear_multicast_users() was removed as unused
in commit 2173f8d953e7 ("netlink: cleanup tap related functions").
Update the comment in netlink_change_ngroups() to remove the stale
reference, replacing it with a general description of the behavior
while preserving the warning.

Assisted-by: unnamed:deepseek-v3.2 coccinelle
Signed-off-by: Kexin Sun <kexinsun@xxxxxxxxxxxxxxxx>
---
 net/netlink/af_netlink.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 4d609d5cf406..018d33af25ad 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2108,8 +2108,8 @@ int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
  * This changes the number of multicast groups that are available
  * on a certain netlink family. Note that it is not possible to
  * change the number of groups to below 32. Also note that it does
- * not implicitly call netlink_clear_multicast_users() when the
- * number of groups is reduced.
+ * not implicitly clear listeners from groups that are removed when
+ * the number of groups is reduced.
  *
  * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
  * @groups: The new number of groups.
-- 
2.25.1