Fix for DMA's in FS caches.

Fix for DMA's in FS caches.
Fix CSHR's for flow control.
Fix for Bus Bridges reusing packets (clean flags up)

Now both timing/atomic caches with MOESI in UP fail at same point.

src/dev/io_device.hh:
    DMA's should send WriteInvalidates
src/mem/bridge.cc:
    Reusing packet, clean flags in the packet set by bus.
src/mem/cache/base_cache.cc:
src/mem/cache/base_cache.hh:
src/mem/cache/cache.hh:
src/mem/cache/cache_impl.hh:
src/mem/cache/coherence/simple_coherence.hh:
src/mem/cache/coherence/uni_coherence.cc:
src/mem/cache/coherence/uni_coherence.hh:
    Fix CSHR's for flow control.
src/mem/packet.hh:
    Make a writeInvalidateResp, since the DMA expects responses to it's writes

--HG--
extra : convert_revision : 59fd6658bcc0d076f4b143169caca946472a86cd