staging: comedi: mite: don't expose CHSR_* bit defines

These bit defines are only used in the mite driver. Move them so they
are not needlessly exposed.

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>