Use SimpleMemory instead of DDR3 so we can use the timing results in tests. By using SimpleMemory, even if the DRAM timing changes the timing of this test won't change. I expect the timing of SimpleMemory to never change. Change-Id: I4c75981d7b8bfc4dcca59e628e89f5a6ea4c0e36 Signed-off-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17871 Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>