hdl/dsp_cores_pkg.vhd: add machine translation functions

As we have different machine parameters for some modules,
it is convenient to have some utility functions to select
the parameters accordingly
hdl/*/position_calc_core_pkg.vhd: remove duplicated function

The function is already inside dsp_cores_pkg package
hdl/modules/sp_cores_pkg.vhd: add machine name constant

This is a temporary solution to supporting multiple
ring parameters. This constant should be modified
to the correct machine name as needed
hdl/*/position_calc/generated/*: add parametrized function

Instead of hardcoded filename paths we use a utility function
that does the job for us.