Revert "uio: use request_threaded_irq instead"

Since mutex lock in irq hanler is useless currently, here will
remove it together with it.

This reverts commit 9421e45f5ff3d558cf8b75a8cc0824530caf3453.

Reported-by: [e-mail]
CC: Ahsan Atta <[e-mail]>
Signed-off-by: Xiubo Li <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/uio/uio.c

···
 	struct uio_device *idev = (struct uio_device *)dev_id;
 	irqreturn_t ret;
 
-	mutex_lock(&idev->info_lock);
-
 	ret = idev->info->handler(irq, idev->info);
 	if (ret == IRQ_HANDLED)
 		uio_event_notify(idev->info);
 
-	mutex_unlock(&idev->info_lock);
 	return ret;
 }
 
···
 		 * FDs at the time of unregister and therefore may not be
 		 * freed until they are released.
 		 */
-		ret = request_threaded_irq(info->irq, NULL, uio_interrupt,
-					   info->irq_flags, info->name, idev);
-
+		ret = request_irq(info->irq, uio_interrupt,
+				  info->irq_flags, info->name, idev);
 		if (ret)
 			goto err_request_irq;
 	}