Various fixes to delete packet and request a little better.

Various fixes to delete packet and request a little better.

src/cpu/simple/timing.cc:
    Various updates for deleting requests more properly.

    The major change is moving the deletion of the fetch request/packet to after the instruction has executed and completed.  This should fix a few bugs because Ron's memory system didn't expect a call for a functional access while a timing access was being processed.

--HG--
extra : convert_revision : c7cf114bb1ff3cdaa7b0a40ed4c5302dc9d3a522