staging: comedi: mite.h: whitespace changes in function declarations

Reformat some function declarations to avoid bunching up near column 80.

Also add a blank line after a `struct` definition.

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>