selftests: arm64: Don't log child creation as a test in SVE ptrace test

Currently we log the creation of the child process as a test but it's not
really relevant to what we're trying to test and can make the output a
little confusing so don't do that.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210913125505.52619-3-broonie@kernel.org


Signed-off-by: Will Deacon <will@kernel.org>