tests: Removed realview tests from .testignore

tests: Removed realview tests from .testignore

The tests still fail, as recorded in
https://gem5.atlassian.net/browse/GEM5-364, though they have been
removed from the .testignore file as part of our goal of removing the
.testignore directory: https://gem5.atlassian.net/browse/GEM5-361.

Change-Id: I74f8a6c86e24835acbb4891ab4c88320baf12346
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33134
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>