Input: psmouse - replace flush_workqueue() with disable_delayed_work_sync()

Input: psmouse - replace flush_workqueue() with disable_delayed_work_sync()

The original code uses flush_workqueue() in psmouse_disconnect() to
ensure the completion of both resync_work and dev3_register_work.
Given that alps_disconnect() already uses disable_delayed_work_sync()
to cancel dev3_register_work, replacing flush_workqueue() with
disable_delayed_work_sync(&psmouse->resync_work) is more robust
and efficient.

Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://patch.msgid.link/6e40a46e5d9e6e3237702958b8f641263c28d2e4.1765939397.git.duoming@zju.edu.cn
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>