platforms: update run_model parameter to use iris interface

The scripts launch models by default using CADI connection. This
is now deprecated. Iris is now the standard for model connections.
Replace -S parameter in run_model scripts with -I to reflect the
above update.

Change-Id: I388993fba4d9dbdeb8dca6239bfe401e4b41297a
Signed-off-by: Jerry Wang <Jerry.Wang4@arm.com>