staging: comedi: put module _after_ detach

On failure of the call to the low-level comedi device driver's
`->attach()` handler from `__comedi_device_attach()`, reverse the
current ordering of the calls to `module_put()` and
`comedi_device_detach()` because `__comedi_device_detach()` will call
code in the module being put.

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>