attempt at cleaning up CLIC parameter definitions

[dansmathers]

No description provided.

[dansmathers]

maybe we should specify the parameters the same way as legal values are specified in https://github.com/riscv-software-src/riscv-config yaml files, e.g.
https://github.com/riscv-software-src/riscv-config/blob/master/docs/source/yaml-specs.rst

To represent the set {0, 1, 2, 3, 4, 5}

[0:5]

To represent the set {5, 10, 31}

[5, 10, 31]

To represent the set {2, 3, 4, 5, 10, 11, 12, 13, 50}

[2:5, 10:13, 50]

[kasanovic]

Looks like several discrete updates - can we please split into separate PRs?

[dansmathers]

Closing due to pull #369