sonypi: don't use flush_scheduled_work()

flush_scheduled_work() is deprecated and scheduled to be removed.
Directly flush sonypi_device.input_work on removal instead.

Signed-off-by: Tejun Heo <[e-mail]>
Cc: Mattia Dongili <[e-mail]>

drivers/char/sonypi.c

···
 	sonypi_disable();
 
 	synchronize_irq(sonypi_device.irq);
-	flush_scheduled_work();
+	flush_work_sync(&sonypi_device.input_work);
 
 	if (useinput) {
 		input_unregister_device(sonypi_device.input_key_dev);