staging: comedi: make 'in_request_module' a bool bit-field

Change the `in_request_module` member of `struct comedi_device` to a
1-bit bit-field of type `bool` and move it into a suitable hole in the
data type to save a few bytes.  Change the assigned values to `true` and
`false`.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>