staging: comedi: mite: use module_init()/module_exit()

Rename the standard `init_module()` and `cleanup_module()` functions and
make them static.  Use `module_init()` and `module_exit()` to mark the
renamed functions as the module init and exit functions.

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>