ipmi: Remove unused struct watcher_entry

After commit e86ee2d4("ipmi: Rework locking and shutdown for hot remove"),
no one use struct watcher_entry, so remove it.
Signed-off-by: Yuan Can <yuancan@huawei.com>
Message-Id: <20220927133814.98929-1-yuancan@huawei.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmi_msghandler.c

@@ -736,12 +736,6 @@ static void intf_free(struct kref *ref)
 	kfree(intf);
 }
 
-struct watcher_entry {
-	int              intf_num;
-	struct ipmi_smi  *intf;
-	struct list_head link;
-};
-
 int ipmi_smi_watcher_register(struct ipmi_smi_watcher *watcher)
 {
 	struct ipmi_smi *intf;