LSQ: Fix a few issues with the storeset predictor.
LSQ: Fix a few issues with the storeset predictor.

Two issues are fixed in this patch:
1. The load and store pc passed to the predictor are passed in reverse order.
2. The flag indicating that a barrier is inflight was never cleared when
   the barrier was squashed instead of committed. This made all load insts
   dependent on a non-existent barrier in-flight.

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