staging: comedi: me4000: remove struct me4000_cnt_context

The me4000_cnt_contect simply holds the unsigned long i/o addresses
used to read/write the counter registers. Thes can be calculated
as needed. Remove the struct and the associated field in the
private data.

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>