staging: comedi: comedidev.h: add namespace to the subdevice "runflags"

Tidy up and document the subdevice "runflags". Rename them so they have
comedi namespace.

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>