staging: comedi: amplc_dio200_common.c: fix up brace style

Use braces when the single statement following an `if` (or `else`)
spans more than one line (including any preceding comments).

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>