staging: comedi: hwdrv_apci3501: rename 'ul_Command1' in apci3501_config_insn_timer()

Rename this CamelCase local variable.

For aesthetics, split the mask/set operations.

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