More changes toward making simpleCpu use new port interface.

More changes toward making simpleCpu use new port interface.

cpu/simple/cpu.cc:
    Initialize the ports, also add Request and Packet instead of MemReq.  Initial work at ICache read in place.
cpu/simple/cpu.hh:
    Need to call the completion handler when we see a recieve.

--HG--
extra : convert_revision : a52caee6f0ceb5d9ee1e5acca63a202f5ea71359