remove "where X denotes Y" from algorithms

[fcelda]

Elliptic Curve VRF section enumerates used primitives and notation used in algorithms below (https://tools.ietf.org/html/draft-goldbe-vrf-01#section-5). Clarifying what operation is meant in the algorithm steps is disruptive.

In case of *, if we want to differentiate between integer multiplication and EC point addition, we can specify both as primitives. Used operation must be clear from the context because the input types are always clear.