staging: comedi: pcl818: remove pcl818_check()

This function is a _very_ simplified probe that tried to verify that
the driver is being attached to a PCL-818 compatible board. The function
simply writes some values to specific registers then reads back the
values to see if they are the same.

It's possible that the user could try to attach this driver to a non-
compatible board but the check would still pass depending on the register
map of the board.

Just remove the buggy function to simplify the attach a bit.

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>