increase MIMO to hold 16 8-byte data words in each direction of MemSlaveEngine

Change-Id: I6dc1f0a97be5ef8717973dcdef40ae27d45a151b
should be able to send header tlp a cycle earlier for 4dw writes in MemSlaveEngine

Change-Id: I75f40772e2d4308bc1f716e7147f062f7ce5eee2