FlushW prevents writting the cache, dtim, and bus state. FlushW still gates HTRANS.
FlushW does not impact the mealy outputs of the cache and bus FSMs and hazard is updated to
not stall W if we get a trap.
We had instruction fetches fixed HSIZE = 2 (4 bytes) for all requests. It should be HSIZE = 3 (8 bytes) for cache fetches and 4 for uncached reads. The reason this worked for non burst is the DDR4 memory controller returns the full double word even for 4 byte reads. In burst mode the second beat ending up pointing to the next 4 bytes rather than the next 8 bytes.
