o3: move arm_v7a-like config to the o3 directory
when this is in the Simulation directory, it prevents the running of other CPU models if O3 isn't
compiled in, which obviously isn't desirable. You can replicate this error by just compiling
the InOrderCPU model (or SimpleTiming) and trying to run hello world.
There may be a cleaner way to do this without actually compiling in the arm_v7a-like config into gem5 but
I dont know of one currently