tests: Moved realview config files

tests: Moved realview config files

This is part of a process of getting rid of the `tests/config`
directory, and placing these configs either where they are used,
removing them if unneeded, or moving them to `configs/example`.

These config files, in this patchset, are part of the realview tests
found in `tests/gem5/fs/linux/arm/`. They have been moved to
`tests/gem5/configs`.

Change-Id: I7706b59c58da6413f5f3dd816a1e5cd54a834a58
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33143
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>