rockchip: saradc: remove double semi-colon

Remove double semi-colon that has been forgotten while adding the
driver. This is only a style fix since it doesn't change the
functionality of the driver.

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>