platforms/rdfremont*: add rss integrity checker param

RSS now requires the integrity checker starting from commit
`2a5c32466 RSS: Add integrity checker driver` in TF-M repo. So,
configure integrity checker in run model script.

Note: This may become the default in future.

Signed-off-by: Joel Goddard <Joel.Goddard@arm.com>
Change-Id: Ic31f1f1db6689a5f5eb717f5b9ee4155d9a257ec