staging: comedi: pcmmio: remove 'continuous' from private data

This member of the private data can be determined from the cmd->stop_src.
Do that instead and remove the member.

Refactor pcmmio_handle_dio_intr() to remove an indent level.

For aesthetics, change the switch in pcmmio_cmd() to an if/else.

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>