staging: comedi: comedi_fops: remove last forward declaration

There is still a forward declaration in this file for parse_insn().
Remove the need for it by moving do_insnlist_ioctl() down a bit.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>