usb: typec: ucsi: Fix NULL pointer access

Resources should be released only after all threads that utilize them
have been destroyed.
This commit ensures that resources are not released prematurely by waiting
for the associated workqueue to complete before deallocating them.

Cc: stable <stable@kernel.org>
Fixes: b9aa02ca ("usb: typec: ucsi: Add polling mechanism for partner tasks like alt mode checking")
Signed-off-by: Andrei Kuchynski <akuchynski@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20250305111739.1489003-2-akuchynski@chromium.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>