staging: nvec: make touchpad init synchronous

Currently, we are constantly sending commands to the EC without waiting for them to be
executed. For the touchpad initialization this only worked because we were waiting 200 µs
between each submitted command byte, so the EC had enough time to execute. In the furture
we like to avoid this delay, so we need to wait for each command to be executed first.
Do this by switching from asynchronous to synchronous command transmission.

Signed-off-by: Marc Dietrich <marvin24@gmx.de>
Link: https://lore.kernel.org/r/20240406123123.37148-4-marvin24@gmx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>