staging: comedi: gsc_hpdi: move the (*auto_attach) helper functions

For aesthetics, move a couple helper functions that are only called
by the (*auto_attach) closer to that function.

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>