Avalon-MM: use BitVectors and remove unused field

[JvWesterveld]

Breaking changes.

Does anyone know what the unused field fixedWaitTime that's removed in the first commit was supposed to be used for?

Perhaps I should also change the irqList field type over to BitVector.

[rowanG077]

I didn't write it. But I expect fixedWaitTime is used to indicate the output needs to be asserted for that many cycles at least. See 3.3.2 Wait-States in https://www.cs.columbia.edu/~sedwards/classes/2008/4840/mnl_avalon_spec.pdf

[JvWesterveld]

Right, it indeed looks like fixedWaitTime concerns the fixed wait-states for write transfers as documented in section 3.3.2.1. So the implementation made sure to only allow connecting managers and subordinates with the same value for this parameter, which makes sense to me now. I'll probably drop the commit.