staging: comedi: refactor me4000 driver to remove forward declarations

Move the struct comedi_driver, attach/detach functions, and
associated variables to the end of the source. This is more
typical of how other drivers are written and removes the need
for most of the forward declarations.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>