Input: appletouch - initialize work before device registration

Syzbot has reported warning in __flush_work(). This warning is caused by
work->func == NULL, which means missing work initialization.

This may happen, since input_dev->close() calls
cancel_work_sync(&dev->work), but dev->work initalization happens _after_
input_register_device() call.

So this patch moves dev->work initialization before registering input
device

Fixes: 5a6eb676 ("Input: appletouch - improve powersaving for Geyser3 devices")
Reported-and-tested-by: syzbot+b88c5eae27386b252bbd@syzkaller.appspotmail.com
Signed-off-by: NPavel Skripkin <paskripkin@gmail.com>
Link: https://lore.kernel.org/r/20211230141151.17300-1-paskripkin@gmail.com
Cc: stable@vger.kernel.org
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/appletouch.c

@@ -916,6 +916,8 @@ static int atp_probe(struct usb_interface *iface,
 	set_bit(BTN_TOOL_TRIPLETAP, input_dev->keybit);
 	set_bit(BTN_LEFT, input_dev->keybit);
 
+	INIT_WORK(&dev->work, atp_reinit);
+
 	error = input_register_device(dev->input);
 	if (error)
 		goto err_free_buffer;
@@ -923,8 +925,6 @@ static int atp_probe(struct usb_interface *iface,
 	/* save our data pointer in this interface device */
 	usb_set_intfdata(iface, dev);
 
-	INIT_WORK(&dev->work, atp_reinit);
-
 	return 0;
 
  err_free_buffer: