cpu-o3: fix atomic instructions non-speculative

Fix problem with O3 and AMO instructions. At initial stages amo
instruction is considered a type of non-speculative store. After
the instruction has been commited and during the squash step,
acquire_release version of the AMO operation is considered speculative,
that differents results in an assert fault. This fix ensures that AMO
instructions are always considered non-speculative, during early stages
and during squas/removal of the instruction.

Change-Id: Ia0c5fbb9dc44a9991337b57eb759b1ed08e4149e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19815
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/cpu/o3/inst_queue_impl.hh

@@ -1262,7 +1262,6 @@ InstructionQueue<Impl>::doSquash(ThreadID tid)
 
             bool is_acq_rel = squashed_inst->isMemBarrier() &&
                          (squashed_inst->isLoad() ||
-                          squashed_inst->isAtomic() ||
                           (squashed_inst->isStore() &&
                              !squashed_inst->isStoreConditional()));