cifs: print last update time for interface list

We store the last updated time for interface list while
parsing the interfaces. This change is to just print that
info in DebugData.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifs_debug.c

@@ -456,8 +456,10 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 
 			spin_lock(&ses->iface_lock);
 			if (ses->iface_count)
-				seq_printf(m, "\n\n\tServer interfaces: %zu",
-					   ses->iface_count);
+				seq_printf(m, "\n\n\tServer interfaces: %zu"
+					   "\tLast updated: %lu seconds ago",
+					   ses->iface_count,
+					   (jiffies - ses->iface_last_update) / HZ);
 			j = 0;
 			list_for_each_entry(iface, &ses->iface_list,
 						 iface_head) {