comedi: jr3_pci: Fix synchronous deletion of timer

When `jr3_pci_detach()` is called during device removal, it calls
`timer_delete_sync()` to stop the timer, but the timer expiry function
always reschedules the timer, so the synchronization is ineffective.

Call `timer_shutdown_sync()` instead.  It does not matter that the timer
expiry function pointer is cleared, because the device is being removed.

Fixes: 07b509e ("Staging: comedi: add jr3_pci driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20250415123901.13483-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: ian-abbott

drivers/comedi/drivers/jr3_pci.c

@@ -758,7 +758,7 @@ static void jr3_pci_detach(struct comedi_device *dev)
 	struct jr3_pci_dev_private *devpriv = dev->private;
 
 	if (devpriv)
-		timer_delete_sync(&devpriv->timer);
+		timer_shutdown_sync(&devpriv->timer);
 
 	comedi_pci_detach(dev);
 }