hammer: fixed dma uniproc error
hammer: fixed dma uniproc error

Fixed an error reguarding DMA for uninprocessor systems.  Basically removed an
overly agressive optimization that lead to inconsistent state between the
cache and the directory.

andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin