generic_timer is no longer in the return value of _on_chip_devices. We should correct the _on_chip_devices. Furthermore, to prevent the timer conflict with the fastmodel, we should remove unwanted timer. Change-Id: I6ec7f9749546df3e8f125a5b96e7ed83cab2ea56 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36379 Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com> Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com> Tested-by: kokoro <noreply+kokoro@google.com>