Support values that have both multipliers and adders

[rsnancollas]

The spec can't currently support: 0.3 VDD + 0.07

We might want to change our fields to:
relativeValueMultiplier
relativeValueAdder
relativeValueReference
relativeValueType [min, max, typ]

Aline also pointed out that this doesn't cover min/max, like the max values is 0.3 VDD + 0.07.

We might want another field to specify what type of value it is (an enum that has the values: min, max, typ)

[rsnancollas]

Aline and Rachel to discuss offline.

[asadate]

I came across this issue again while running an example. Let's update the values specs to add this in the next rev. We can discuss in the Industry WG.