staging: comedi: pcl711: remove 'i8253_osc_base'

This static const int variable is only used one place in the code.
Remove it and just open code the value.

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>