Platform: RSE: Rename RSE platform files

Renames all 'rss' files to 'rse'. Avoids changes unrelated to moving
files in this commit to keep to commit history clearer.

Signed-off-by: Jamie Fox <jamie.fox@arm.com>
Change-Id: I321aa2cdff6117c869a7128d2866207efd9b3309
312 files changed