add uglyiness to fix dmas

add uglyiness to fix dmas

src/dev/io_device.cc:
    extra printing and assertions
src/mem/bridge.hh:
    deal with packets only satisfying part of a request by making many requests
src/mem/cache/cache_impl.hh:
    make the cache try to satisfy a functional request from the cache above it before checking itself

--HG--
extra : convert_revision : 1df52ab61d7967e14cc377c560495430a6af266a