staging: comedi: pcmuio: tidy up pcmuio_start_intr()

Refactor this function a bit to remove the need for an extra indent
level and cleanup some of the odd line breaks.

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