usb: ucsi: Add missing ppm_lock

Calling ->sync_write must be done while holding the PPM lock as
the mailbox logic does not support concurrent commands.

At least since the addition of partner task this means that
ucsi_acknowledge_connector_change should be called with the
PPM lock held as it calls ->sync_write.

Thus protect the only call to ucsi_acknowledge_connector_change
with the PPM. All other calls to ->sync_write already happen
under the PPM lock.

Fixes: b9aa02ca

 ("usb: typec: ucsi: Add polling mechanism for partner tasks like alt mode checking")
Cc: stable@vger.kernel.org
Signed-off-by: "Christian A. Ehrhardt" <lk@c--e.de>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20240121204123.275441-2-lk@c--e.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>