[ Upstream commit a342083a ]

We should be using flush_delayed_work() instead of flush_work() in
matrix_keypad_stop() to ensure that we are not missing work that is
scheduled but not yet put in the workqueue (i.e. its delay timer has not
expired yet).
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>