staging: comedi: s626: #ifdef out a block of unused code

Currently the unused s626_ai_rinsn() function is commented out with
/* ... */ on every line of the function. Remove those by using an

This block will be removed once it is determined that it really
is not needed.

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