boards: fvp_baser_aemv8r: enable cache_state_modelled

Let FVP_BaseR_AEMv8R simulate the operation of cache-related.

This will slow the speed of FVP_BaseR_AEMv8R but it can obtain realistic
simulation results as much as possible. So the timeout_multiplier needs
to be increased.

Signed-off-by: Huifeng Zhang <Huifeng.Zhang@arm.com>