arm, configs: Do not forward snoops from I cache
arm, configs: Do not forward snoops from I cache

This fix simply tells the I cache to not forward snoops to the fetch
unit (since there is really no reason to do so).
(transplanted from 8a7285d6197eb0d8f1642e6cdb7a21aa1ff6310e)

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