net: kcm: kcmproc.c: Fix RCU list suspicious usage warning

This path fixes the suspicious RCU usage warning reported by
kernel test robot.

net/kcm/kcmproc.c:#RCU-list_traversed_in_non-reader_section

There is no need to use list_for_each_entry_rcu() in
kcm_stats_seq_show() as the list is always traversed under
knet->mutex held.

Reported-by: kernel test robot <[e-mail]>
Signed-off-by: Madhuparna Bhowmik <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/kcm/kcmproc.c

···
 	aggregate_strp_stats(&knet->aggregate_strp_stats,
 			     &strp_stats);
 
-	list_for_each_entry_rcu(mux, &knet->mux_list, kcm_mux_list) {
+	list_for_each_entry(mux, &knet->mux_list, kcm_mux_list) {
 		spin_lock_bh(&mux->lock);
 		aggregate_mux_stats(&mux->stats, &mux_stats);
 		aggregate_psock_stats(&mux->aggregate_psock_stats,