pce-322a: Pass driver dev_close callback std_serial_dev_acquisition_stop()

All drivers with the exception of pce-322a pass their dev_close callback to
std_serial_dev_acquisition_stop(). The pce-322a passes std_serial_dev_close()
which is also called from its dev_close() callback and replicates the other
functionality of its dev_close() callback directly in
std_serial_dev_acquisition_stop().

Refactor this to pass the dev_close callback function directly to
std_serial_dev_acquisition_stop(). This makes sure that the driver is
consistent with other drivers and also removes duplicated code.

Signed-off-by: Lars-Peter Clausen <redacted>