There is logic in the broadcast hub to skip the outer acquire if there
is an outgoing release, since the data will be written out through the
release channel. However, this will cause an issue in the case of
PutBlock requests. If the tail beats of the PutBlock show up after the
outer release has already been sent, the data will be corrupted.
The fix is to make the outer release block if there are pending
inner PutBlock beats.
A lot of utility code was just being imported willy-nilly from one
package to another. This moves the common code into util to make things
more sensible. The code moved were
* The AsyncQueue and AsyncDecoupledCrossing from junctions.
* All of the code in rocket's util.scala
* The BlackBox asynchronous reset registers from uncore.tilelink2
* The implicit definitions from uncore.util
