platforms/rd: remove unsupported model parameters

Few of the model parameters now have fixed value and so the model
run-script does not have to set them anymore. Accordingly, remove those
parameters from the model run-script.

Signed-off-by: Tony K Nadackal <tony.nadackal@arm.com>
Change-Id: I47b38f179aaf69cbca1d9266117469a00c808884